Firstly welcome to the board.

As for the arrow lenght that depends on the type of rest you have the best thing you could do is take the bow to a pro shop and get them to make up the arrows for you.

As to what type of arrow that is really personal preference.
I use Gold Tip 5575 XT's.
You might be better off starting with some Aluminium ones cause you will probably loose some and break some then switch to carbons when you get better.