Newbie Question

[La1cajun]

So my son and I just bought Munchkin card game and ready the rules and gave it a whirl last night. Lots of fun but I have a couple of questions. 1) my turn, I'm in the process of about to start battle, can my son play a monster out of his hand to have an extra monster for me to fight? 2) e d of my turn and I have 7 cards, do I give my son, same level as me, 2 of my cards to make me have 5? Or is that only for lower level. 3) my turn, in battle, can I replace my race card say from elf to warrior if I have it? Thanks Alot. Looking foward to answers. We just played one game but many more to come!