Yes there is no c or f string but you can fret c notes in many places on the fretboard. The lessons for beginners explains this very well. I'm pretty new to playing myself so I don't completely understand this myself. I get it but I don't have a keyboard to refer too. It would make it easy if you have one handy.As far as the pain it is brief if you practice a lot, but I have to admit it does get painful at first now I have to cut the calluses so I can play and stuff falls off my fingers lol. Do the beginners course and you'll be playing songs and stuff in no time.

Welcome and have fun