"One strobe or 2?"
Start with one. You will be shooting in manual mode with this camera. Don't force yourself to adjust two strobes every time while learning camera controls, too.
"DS50 or DS125?"
DS125 for sure. DS is very limited.
"Normal are or ball socket?"
Normal arms are a pain in the a.. I replaced them with ball arms from ULCS. Buy ULCS or TLC arms instead of Ikelites. Much easier to adjust. Don't get carried away on arm length. You don't need it. I've seen wide anlge setups with two strobes seven feet apart. It's not necessary. Get two 8" or smaller double ball arms plus necessary clamps and bases. Positioning is the key for proper strobe use.
"Help would be really appreciated as this is a lot of cash to spend....:o"
It's just the beginning, sigh.......