My long-awaited basement wiring job is finally underway. I'm using a 100A main panel as my sub; it's adjacent to the house panel and will be fed by a 60A breaker. The pre-installed 100A breaker will be used as a disconnect only. I'm planning on using 6-3 nm-b copper wire to feed the sub (approximate wire length: 6'-7').

Question 1:
Will a new grounding rod be required for this panel? I think the answer is no, but I've read a few different things that have me questioning my research.

Question 2:
Since this is unfinished space, I believe code requires everything except for dedicated outlets to be GFCI protected. I can buy one 60A GFCI breaker for about $100, or I can pick up individual 20A breakers for $30 per. Since I'm making 2 separate runs to 3 rooms plus another single run to each of 3 more rooms, the second option will cost around $300. Aside from cost, is one of these options better than the other? If I'm running two 10A or 15A tools from circuits on one leg of the power, will that cause problems with the GFCI? I'm pretty sure it's not a problem, but once again I figured I'd ask while the asking's good

I don't think I can use a GFCI outlet to protect the entire run:
I'm running all wires 18"aff. Single gang boxes are placed every 6' or so: it's an attempt to meet finished space codes if I decide to finish the rooms. At each single gang box, a splice / pigtail is run to a double box at 50" aff for my shop outlets. Per my current plan, all of the outlets are on brances from the main line; none of them are (currently) able to interrupt the entire chain.

Bonus question: How the heck do people manage to wire nut 3 or 4 12ga wires? I've had a hard time pig-tailing the wires at each junction. I've resorted to holding the wires with one set of smooth jaw pliers, twisting them around 3-4 times with another set of pliers, and then cutting off all but 1/2" of the twisted connection. If I get lucky and the wire doesn't unravel, I can get the wire nuts on.

Thanks!
Jay M