the breakin is the same level of hardness for all nitro engines more or less. Its not that hard but it can be boring and tedious. It is however critical that you do it completely and as accurately as you possibly can.
As for fuel, any 20-30% nitro fuel will work but its best to stick to the brands that are known to work well. VP, Byrons, Odonnell's, and I know I'm forgetting a few more that people can chime in with. I'm drawing a blank for some season. The main 2 I use are Byrons and Odonnells so those spring right to my mind but there are other good ones as well.
i would recommend the firestorm over the bullet as it has a reputation for being a better quality kit but its nearly the same as teh Rustler with only a fraction of the part support. i actually prefer HPI over Traxxas most of the time so its not like I'm a traxxas guy and just trying to push the traxxas brand but out of the 3 kits you listed here the rustler is the best one IMO.