to make rex files you have to use recycle. this program is super handy, basicly what it does is takes a drum beat, or even just a sound file and splices it into a bunch of pieces. you then organise the pieces to your liking which brodens your freedom.
i dont really listen to much hip hop or make it at all, but to explore your creativity you just have to figure out a few things about reason, and then keep learning more. its got so much to it i doubt anybody really knows how to use it fully. but keep playing around with new things and shit starts to improve.
refills are just collections of samples and patches. some are friggin aweseom, but then sometimes people think they're gonna be all cool and make there own just cause they can, and they bundle up a bunch of crap and you download it and delete it right away
id say if you make a beat on reason then it is all yours. i highly doubt all the big music producers use their own samples
and if you decide to use the loops and drumbeats that come with reason, or other refills, i dont think any copyright infringment problems would come your way, if they didnt want you to use their shit they wouldnt put it in a refill in the first place
hopefully this was a little helpful
