Yeah, it is pretty much all preference, there is no 'right' answer as far as gauge and brand go. I prefer lighter strings because it feels like I am fighting the instrument less, but others go the complete opposite. I keep my LP style instrument with thicker strings because it is nice to have the option and it just feels right with that instrument. It really is a matter of whatever works for you, do not let anyone tell you otherwise. While I would suggest experimenting, something to consider is that when you change gauges you will almost certainly have to readjust your intonation for the new gauge. Most guitars it is not super difficult or anything, but if you are afraid of that kind of stuff it is something to consider as well. Most people get a comfort zone of string gauge/type and brand that they like. I have played through most of the major brands myself and have my own preferences. As far as changing goes, I personally draw the line when they are noticeably rusty. The D'addarios and Dunlops (my preferential brands) usually last at least a month before that starts to happen, give or take a few weeks depending on the humidity and how much I wail on them. I know some people play them until they literally break, and some people will change them almost constantly so they always have that wonderful new string feel. Whatever floats your boat. Also, wipe your strings when you are done playing. It takes like one minute and it will greatly enhance the life of your strings. So basically everyone here has given you good advice. Last thing, is that I would spend more time with any decent brand names regular strings before moving onto things like NYXLs. NYXLs are nice strings, but they are 2x the cost and in my opinion pretty diminishing returns unless they offer you something that you really want. I played through a few packs of the expensive strings I got on sale and found them to perform fairly similarly to the same brands regular strings, and in the NYXLs case they did not last any longer either. YMMV.