[Standard] [Opinion] Whte red angel deck

Hi, I'm completely new to Magic having bought my first deck only a month ago. With a deck builder toolkit, I cobbled together this angel deck , which Sadly is somewhat unstable. I use red to put in many tokens to fend of early game strikes while I built towards the larger white creatures. I've splashed in some protection and destruction spells to buy me more time. I've built this deck intending for casual play( mostly against my brothers oversized golgari growth deck ). Right now, the deck always seemto either give me too much mana, or too little, so even my brothers 90~100 card deck is beating me time and time again. http://deckbox.org/sets/317749
Here are my questions:
1, what is an ideal mana curve for a late game large creature deck like this one?
2, what sort of cards could this do with and what should I just throw right out? I don't intend for exact cards, just a general card type. As in maybe I need more destruction spells or more cheap creature spells, that kind of thing.
3, how many lands should I be running? I'm currently at 24.
4, if my mana curve is very far off, what should I change?
5, finally, under what circumstances should I mulligan?
I'm very new to this, so I would like to request being given advice in Laymans terms. Thx much