#1
so i just realized a very purplexing paradox with my playing, whenever im learning song I spend hours of hard work learning but once i actually learn in its completetion I dont feel like playing it as much and immediately move to the next song however i tend to forget old songs that i learned previously my range of songs is pretty elaborate and im finding it hard to learn new matieral and not forget old matieral, how can i organize my practice sessions to balance my retainment of old matieral and new songs that im learning? btw my range is pretty wide i play things from chilli peppers to slayer and find it hard to find a middle ground
#3
Maybe keep a list of your repertoire. This will make it easier to remember, "hey, I spent x hours learning that whole song. I think I'll play that now"

Also figure out your goals. If you want to play in a cover band, practice a core group of songs and get them sounding good. If you want to learn lots of new techniques, keep learning lots of new songs with particular techniques in them. If you're just playing for fun and don't need any goals, just keep doing whatever feels good.
#4
Yeah I wouldn't worry that much. Most musicians who have a large repertoire to draw from have done exactly what you did, but joined groups that continually played those tunes.

Chances are if you do not remember it, you are not incorporating what you learned into your playing. Whether that is good or bad is up to you. Trying to remember every single song you have learned is mostly likely a waste of time.