Got a bunch of questions topic

i just spent 8 hours getting bootloader unlocked.
now i got a bunch of questions. hope it can save me a lot of time from studying for another 30+ hours, this sure is hard to get to work for me XD.

so these 2 links are talking a bought stuff. i have not been able to Google/find answers on yet.

http://forum.xda-developers.com/shie...lipop-t2945044
http://forum.xda-developers.com/shie...hield-t2848064

What is CWM,SuperSu and CWM Recovery for and do?

do i need to do these.
also i am on version android 4.4.2 stock version. should i update to a newer version. and is it safe to update?

also if so how or which programs should i use to root device.
also whats the top 10 suggested apps to get.

what should i update too? and what is the worth of updating? any better performance in device?
i use to have an apple device but every-time it got updates it got slower so i am curious.