Well, that's a pretty straight forward set of questions.


servos are going to be determined by the amount of force necessary to drive the control surface. You go all the way from 9g micro servos, to the monstrosities built for 1/2 scale stuff. Gearing can be important as well, some servos are metal geared while some are plastic.

Digital I will leave for someone else, I don't have a brilliant answer for that.

Yes you can mix and match servos. My tiger is stacked out in all hobbico and futaba servos(because I used futaba for 4 years), but I'm using a JR based radio. There are a few exception for much older airtronics servos, but I doubt you will encounter that. The because hurtle to using a futaba/jr mix and match is trimming the alignment tab of the futaba plug....