1.) The pool of trained crew for your ships increases over time based on how many naval academies you have. Each academy also produces 5 officers/year. These officers are for all 4 types: Naval, Ground, Scientists, and Administrators. If you have changed the base crew grade (see race details left side) to something other than the starting 1 you will get fewer people added to the crew pool. You can set the rating from 1 to 5, use that as the divisor on the number of crew per year you will receive. Also changing the base grade will cut the pool you have in half. Personally I wouldn't change the rating to start with. You will probably have plenty of time to train your crews up and the reduction in the pool of trained people is just not worth it. You can always change it later and probably have more total crew available for the higher training settings.
2.) Each GFTC will work totally independently. If you want to produce more ground forces the only thing that will help is to have an Administrator with a ground combat training speed bonus. I have been known to set up a planet with enough mines to support the training facilities and build up a ground force training planet just to take advantage of a 30% speed increase.
Brian