Greases and cleaners

I am a bit confused about all the different greases that are there in bike shops. What grease should I use if I ware to open up a bearing and regrease it? Is there one general grease that I can use on axles, bolts, dropper post, hubs, bearings when doing usual maintenance? Also, for cleaning all the stuff like fork stanchions (when servicing), dropper and all other stuff that is oily i use paint dillutant, maybe there is better options, maybe I should use brake cleaner?