Couple of additions to Agrajag's post:
1) Here is the
abbreviations post
2) Yep,
Conceptual Balance Mod (CB) is the most common.
3) I believe Nile is pretty popular for duels. Otherwise there isnt a common one that I know of. Aran maybe since its kind of default?
5) Gem generators (clams, fetishes, etc) are good, but it should be noted that they are not as good as in CB. Probably the most popular item would be the Dwarven Hammer which gives you a forge bonus. Also, pay close attention to all the "booster items" (items which increase the wielders power in a magic path).
8) Newbie games do start in the MP forums occassionally. You can also see if someone will host one for you and then just advertise your own game in a post.
10) If you are just casting a particular spell or spells, its probably not neccessary to max out a magical path. Maxing your magic paths (going to 9-10) is usually reserved for Bless Strategies as each additional pick of magic gets more and more expensive. If you were to take like 5-7 in a path and then use booster items to get you as high as you needed, that would probably be a more efficient use of your design points.