^ Anybody can play 1B without much penalty because it's at the easy end of the spectrum, just be wary of moving D- range players there. That would be an interesting question about an OF moving to 3B? I'm assuming all OFs are treated equally by the Sim and none are assumed to be CFs though that's just a guess.
Regarding the 2B/3B question, 3B has the long throw and sharp reflexes but 2B more important because greater range more movement the double play factor and tagging out basestealers adds up to more significance,.