Seetings.

[Oladefe]

After doing a little bit of thinking I decided to start another thread (I was going to put this in my previous thread, "How much?", but I thought that those who already have looked at it would ignore it

Like I previously said, I was asked to do a party. Also, as I stated, I have never had any contact with commercial photography. My question is what settings I should use for the event? I own a Sony Alpha 100. What do you think would be the best settings to take the photos as well as for printing them (size). Should I shoot .RAW?
I currently have only two lenses (18-70mm F 3.5-5.6 and the 75-300mm F 4.5-5.6) and no external flash. My another question is should I invest in a faster lens (the room is probably going to be dark) and an external flash? If so, which lens would you recommend (I don't want to spend above $400 for a lens and an external flash) http://www.sony.net/Products/dslr/lenses.html.
Thank you for taking your time and reading this.