Giving the living a share of the reward for charity
Question

                I hope that you can advise me about this method that I follow every day and that I learned from one of my friends; it is a very easy way of giving charity every day. 

What I do is put a box for money, and every day I put whatever I can in it, of any amount, even if usually it is very small, equivalent to one Saudi riyal (to explain to you how much it is). And I form the intention to give charity as well as reciting whatever I want of du‘aa’, and I do not forget to ask Allah to regard it as charity on my behalf and on behalf of all the Muslim men and women and believing men and women, both living and dead, in sha Allah. 

Is this daily charity permissible and is it regarded as acceptable and a suitable amount?

Can I change it for bills or notes of an equivalent amount in order to have more room in the box and use these small amounts again? 
Is it permissible to collect it and give it in charity to a needy person in one go?.
Praise be to Allah.
    Firstly:

    It is mustahabb to give charity to one who is in need, even 
    if it is something small, because the Prophet (blessings and peace of Allah 
    be upon him) said: “Protect yourselves from the Fire even if it is with half 
    a date.”

    Narrated by al-Bukhaari, 5564; Muslim, 1689 

    It was narrated that Abu Hurayrah (may Allah be pleased with 
    him) said: The Messenger of Allah (blessings and peace of Allah be upon him) 
    said: “Whoever gives charity the equivalent of a date that was acquired by 
    halaal means – for Allah does not accept anything but that which is good 
    (halaal)– Allah accepts it in His right hand, then He tends it for the one 
    who gave it, as one of you tends his foal, until it becomes like a 
    mountain.”

    Narrated by al-Bukhaari, 1321 

    Secondly: 

    Reciting du‘aa’ before giving charity is something that is 
    subject to further discussion. This has been discussed previously in the 
    answer to question no. 98579. 

    Thirdly: 

    It is permissible for a person to give in charity on his own 
    behalf and to intend that others among those who have died have a share of 
    the reward of his charity. This has been discussed in the answer to question 
    no. 102322. 

    With regard to giving a share of the reward for the charity 
    to those who are still alive, this is not mentioned in the Sunnah so it is 
    better not to do it. 

    It says in Zaad al-Mustaqni‘: If a person does any act 
    of worship and dedicates its reward to a deceased Muslim, or one who is 
    still living, that will benefit him. End quote. 

    Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said:

    If a person has died, and one does an act of worship on his 
    behalf, that serves a purpose, because the deceased is in need (of hasanaat) 
    but cannot do any righteous deeds. But if he is alive and is able to do this 
    act, then in that case it depends, because it may lead to the living person 
    depending on this man who is doing an act of worship on his behalf. There is 
    no report that the Sahaabah (may Allah be pleased with them) or the 
    righteous early generations did such a thing; rather what they were 
    accustomed to do was to dedicate the reward for an act of worship to the 
    dead; in the case of those who were still alive, they did not do this, 
    except in the case of an obligation such as Hajj, because that was known 
    from the time of the Prophet (blessings and peace of Allah be upon him), but 
    that is subject to the condition that the person on whose behalf Hajj is 
    performed is incapable in such a way that there is no hope of recovery.

    End quote from ash-Sharh al-Mumti‘, 5/371 

    Fourthly: 

    There is nothing wrong with exchanging pieces of metal for 
    others; rather it is permissible for you to change your mind about this 
    charity, because anything that is given as charity or a gift does not become 
    the property of the recipients unless they take possession of it. If it has 
    not been taken possession of, then the giver has the option to go ahead with 
    it or to change his mind concerning it. See the answer to question no.
    146237 

    Fifthly: 

    The one who wants to give charity has a choice between giving 
    it to one poor person or more, as he sees fit. It is better to give it to 
    relatives if they are in need, because Allah says (interpretation of the 
    meaning): “To an orphan near of kin” [al-Balad 90:15]. 

    And because the Prophet (blessings and peace of Allah be upon 
    him) said: “Charity given to the poor person is charity, but given to a 
    relative it is two things: charity and upholding ties of kinship.”

    Narrated by at-Tirmidhi, 594; classed as saheeh by Shaykh 
    al-Albaani, may Allah have mercy on him. 

    And Allah knows best.