Two questions سؤالين

wa alaykum as salaam wa rahmatullahi wa barakatuh!

Thank you for your questions!

As for the takbirat of the Eid prayers, it is declared seven times in the first rakaat and five times in the second rakaat (Ref. Al-Azhar). If you are praying behind an imam who recites it contrary to this, you would simply follow what the imam does. 

As for raising the hands for the takbirat, those who take the opinion that the hands are not raised at all simply refrain from raising the hands in all the takbirat. As for those who take the opinion that the hands are raised once in the prayer, they only raise them for the takbir al-ihram and not afterwards (Ref. Al-Bahr). 

As for assisting the one who cannot perform the wudu, it is permissible. I could not find a direct source, but I would say that it is common sense to assist people in righteousness and taqwa (Q. 5:2).  

And Allah knows best!

IRS