Reading du`as from pieces of paper when praying qiyaam
Question

I would like to ask whether it is permissible to write du`a’s on a piece of paper and use it whilst praying qiyaam.
I would also like to know whether toothpaste affects the fast or not.
Praise be to Allah.Firstly:
Reciting du`a in Qunut al-Witr is permissible for the imam and the one who is praying alone, because of the report narrated by Abu Dawood (1425) and Ibn Maajah (1178) from al-Hasan ibn ‘Ali (may Allah be pleased with him) who said: The Messenger of Allah (peace and blessings of Allah be upon him) taught me some words to say in qunoot al-witr: “Allahumma’hdinee fiman hadayta wa ‘aafinee fiman ‘aafayta wa tawallanee fiman tawallayta wa baarik lee fimaa a’tayta wa qinee sharra maa qadayt, fa innaka taqdee wa laa yuqdaa ‘alayk. Wa innahu laa yadhillu man waalayta wa laa ya’izzu man ‘aadayt. Tabaarakta Rabbanaa wa ta’aalayt. Laa maljaa minka illa ilayk (O Allah, guide me along with those whom You have guided, pardon me along with those whom You have pardoned, be an ally to me along with those whom You are an ally to, and bless for me that which You have bestowed. Protect me from the evil You have decreed for verily You decree and none can decree over You. For surety, he whom You show allegiance to is never abased and he whom You take an enemy is never honored and mighty. O our Lord, Blessed and Exalted are You. There is no refuge from You except with You).”
Classed as saheeh by al-Albani in Saheeh Sunan al-Nasaa’i. See also question no. 14093.
It is not proven that Qunut al-Witr is something that the Prophet (peace and blessings of Allah be upon him) did, rather it is proven that ‘Umar (may Allah be pleased with him) did it, as was narrated and classed as saheeh by al-Bayhaqi.
Hence some of the scholars are of the view that it is better not to recite al-Qunut all the time, rather one should do it sometimes and not at other times. See al-Sharh al-Mumti’ by Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) (4/19).
Some of the scholars are of the view that one should not recite Qunut except in the second half of Ramadaan. This is the view of al-Shaafa’i and of Maalik in one report.
Al-Shaafa’i (may Allah have mercy on him) said: Qunut should not be recited in Ramadaan except in the second half (of the month). This is what Ibn ‘Umar and Mu’aadh al-Qaari used to do. End quote from Mukhtasar al-Muzani, published with al-Umm (8/114).
Al-Baaji said in al-Muntaqa (1/210): Two reports were narrated from Maalik concerning that, one of which says that Qunut should not be recited in Witr at all, and the other says that it is mustahabb during the second half of Ramadaan, This was reported by Ibn Habeeb from Maalik, and this was also the view of al-Shaafa’i.
Abu Haneefah and Ahmad (may Allah have mercy on them) were of the view that Qunut should be recited throughout Ramadaan, and Qunut may be recited in Witr throughout the year.
Ibn Qudaamah (may Allah have mercy on him) said: Qunut is Sunnah in Witr, in the single rak’ah, throughout the year. This is what is narrated by our companions and this is the view of Ibn Mas’ood, Ibraaheem, Ishaaq and ashaab al-ra’i. It was also narrated from al-Hasan.
Another opinion was narrated from Ahmad, which is that Qunut should not be recited except during the second half of Ramadaan. That was also narrated from ‘Ali and Ubayy, and it was the view of Ibn Sireen, Sa’eed ibn Abi’l-Hasan, al-Zuhri, Yahya ibn Wathaab, Maalik and al-Shaafa’i, and it was the view favoured by Abu Bakr al-Athram, because of the report narrated from al-Hasan, that ‘Umar united the people behind Ubayy ibn Ka’b, and he used to lead them in prayer for twenty nights during which he only recited Qunut in the second half. Narrated by Abu Dawood. This is like consensus.
Qataadah said: Qunut should be recited throughout the year except in the first half of Ramadaan, because of this report. It was narrated from Ibn ‘Umar that he only recited Qunut in the second half of Ramadaan.
And it was narrated that he did not recite Qunut in prayer at all.
The first report is the one that is favoured by most of our companions. Ahmad said, according to the report of al-Marwadhi: I was of the view that it should be done in the second half of Ramadaan, but now I recite Qunut, because it is du`a and is good,and because of the report narrated from Ubayy, that the Messenger of Allah (peace and blessings of Allah be upon him) used to pray Witr, and recite Qunut before bowing. It was narrated from ‘Ali (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) used to say at the end of his Witr: “Allahumma innee a’oodhu bi ridaaka min sakhatika wa bi mu’aafaatika min ‘aqoobatika, wa a’oodhu bika minka. La uhsee thanaa’an ‘alayka, anta kamaa athnayta ‘ala nafsik (O Allah, I seek refuge in Your good pleasure from Your wrath, and in Your protection from Your punishment. I seek refuge with You from You. I cannot praise You enough, and You are as You have praised Yourself.”  He did that all the time, and Ubayy’s action indicates that he saw him. The difference of opinion among the Sahaabah concerning this is not to be criticized, because it is Witr, in which Qunut is prescribed, like the latter half, and because it is dhikr that is prescribed in Witr, so it is prescribed throughout the year like any other dhikr. End quote from al-Mughni (1/447).
Secondly:
One should not make the du`a of Qunut too lengthy, rather al-Baghawi said: It is makrooh to make Qunut lengthy, just as it is makrooh to make the first tashahhud lengthy. [Quoted by al-Nawawi in al-Majmoo’, 3/479]. Al-Qaadi Husayn said: If Qunut is made lengthier than usual, that is makrooh, and may be invalid. [Quoted by al-Khateeb al-Sharbayni in Mughni al-Muhtaaj, 1/167].
One should also avoid that which has been introduced by some imams who turn it into an exhortation by mentioning the grave, the resurrection, the reckoning and so on, which is more suited to sermons and exhortations than du`a and Qunut. If it is limited to the du`a that the Prophet (peace and blessings of Allah be upon him) taught to al-Hasan, or adds a little to that, this is better. It is a short du`a that you should learn by heart, so there is no need to look at a piece of paper.
If you add some other short du`as that were taught by the Prophet (peace and blessings of Allah be upon him), this will be good, and it is easy to do.
But if the imam or the worshipper is not able to memorize the du`as that are to be recited in Witr, there is nothing wrong with him choosing whatever du`as he wishes, because there is no specific du`a to be recited in Qunut, and al-Qaadi ‘Iyaad narrated that the scholars were unanimously agreed on that. [See: al-Majmoo’ 3/477].
Now that we understand that the basic principle concerning the du`a of Qunut is that it is a short du`a, and that making it lengthy is makrooh and contrary to the Sunnah, and that there is no specific du`a to be recited, not even the du`a that is narrated from the Prophet (peace and blessings of Allah be upon him), then there is no need to write the du`a on a piece of paper and read it whilst praying. Rather it seems that the motive for doing that is the desire on the part of imams or worshippers to  recite complicated du`as and to make Qunut lengthy, as is the case with many imams nowadays.
What the worshipper should do is be keen to ponder and focus, because of the report narrated by al-Tirmidhi (3479) from Abu Hurayrah who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: “Call upon Allah and be certain of a response, and understand that Allah does not answer a du`a from a heedless heart.” This hadith was classed as hasan by al-Albani in Saheeh al-Tirmidhi.
Thirdly:
There is no sin on a fasting person if he uses toothpaste, but he should be careful to avoid swallowing any of it.
See also question no. 13619
And Allah knows best.