Is It Obligatory to Wash Body Parts Consecutively in Ghusl?
Question

I did Ghusl following my menses, but I did not rinse out my nose whilst washing. After that, I dried myself off and did a complete Wudu. Does my doing Wudu after Ghusl compensate for what I missed in Ghusl? Was my separating the two by drying myself off a mistake? On the same occasion, I noticed the well-known whiteness on my teeth; do I have to remove it in order to make my Wudu complete?
Praise be to Allah.Rinsing mouth and nose in Wudu and Ghusl
The more correct scholarly view is that rinsing the mouth and nose is obligatory in both Wudu and Ghusl. 
Does Ghusl count as Wudu?
If a man or woman does Ghusl to remove major impurity such as Janabah (a state of major ritual impurity due to semen ejaculation) or menses, this Ghusl counts for Wudu too .
Muslim (327) narrated from Jubayr ibn Mut`im (may Allah be pleased with him) that mention of Ghusl for Janabah was made in the presence of the Prophet (blessings and peace of Allah be upon him) and he said: “As for me, I pour water over my head three times.”
Al-Bayhaqi (may Allah have mercy on him) included this report in a chapter entitled (1/63): Chapter on the evidence for Wudu being included in Ghusl.
Shaykh Ibn `Uthaymin (may Allah have mercy on him) said:
“If a person becomes Junub (a person in Janabah), doing Ghusl suffices for Wudu too, but it is essential to rinse the mouth and nose." ( Fatawa Nur `ala Ad-Darb  120/20)
Is It obligatory to wash body parts consecutively in Ghusl?
The scholars differed as to whether it is obligatory to wash the parts of the body consecutively in Ghusl.
It says in Al-Mawsu`ah Al-Fiqhiyyah (11/200, 102):
“Washing the parts of the body in order and consecutively when doing Ghusl is not obligatory according to the majority of jurists.
Al-Layth (may Allah have mercy on him) said: It is not essential to wash them consecutively. This is a different view from that of Imam Malik; the preferred view according to the scholars who follow his school of jurisprudence is that it is obligatory to do them consecutively, and there is a similar view among the scholars from the school of Imam Ash-Shafi`i.
But according to the view of the majority, if someone does Wudu with Ghusl, he does not have to wash the parts of the body in order when doing Wudu.
Because of that, if he omits to wash one part or a spot of one part, whether it is the parts that are to be washed in Wudu or not, he may wash the part that was omitted on its own afterwards, regardless of whether the time interval is long or short, and if he has washed his body except the parts that are washed in Wudu, he can wash them now, and he does not have to wash them in order.
Because of that, the Shafi`i scholars said: If he omits Wudu, or rinsing the mouth or nose, when doing Ghusl, it is disliked (Makrooh), and it is recommended for him to do those actions, even if a long interval has elapsed, without having to repeat Ghusl. However, according to the Hanafis and Hanbalis, he must make up these actions, because they are obligatory in Ghusl according to them. However, in the case of Wudu, rinsing the mouth and nose is a recommended act according to the Hanafis, and is not obligatory." (Al-Mawsu`ah Al-Fiqhiyyah  11/100-101)
Shaykh Ibn `Uthaymin (may Allah have mercy on him) was asked:
If, after doing Ghusl for Janabah or menses , a woman remembers that she has nail polish on her nails, does she have to repeat her Ghusl?
He replied: 
“According to the Hanbali school of jurisprudence, she does not have to do that, because doing the actions consecutively is not a condition of Ghusl being valid, in their view. However, I believe it is a condition, because if we regard it as a condition in Wudu, then how can it not be a condition in Ghusl? So she must repeat Ghusl." (Thamarat At-Tadwin  p. 21)
What appears to be the case is that your Ghusl is valid, even according to the view that the actions in Ghusl must be done consecutively, because the time that elapsed between Ghusl and rinsing the nose was short, and may not have been more than two or three minutes. Such a short time does not cancel out doing the actions consecutively.
Is Wudu valid if you cannot remove bits of food between teeth?
The whiteness that appears on the teeth is tartar that accumulates on the teeth because of not taking proper care of them or regularly cleaning them with the Siwak or toothpaste.
The scholars of the Permanent Committee for Ifta’ were asked: When we eat, we get some bits of food between our teeth, then when we do Wudu or Ghusl, we cannot remove these bits. Is our Wudu and Ghusl valid?
They replied:
“Wudu and Ghusl are valid even if any bits of food remain between the teeth , but removing them is better." (Fatawa Al-Lajnah Ad-Daa’imah  5/234).
Based on that, your Wudu is valid, but you should regularly clean your teeth and take care of them.
And Allah knows best.