I have an Epiphone Les Paul Classic and the neck is starting to crack at the base. (my cousin knocked it off the stand)

1. Is there anything I can do to stop it from cracking any more through regular playing??

2. If it does indeed break, is my guitar trashed??
It's a long way to the top, If you wanna rock and roll
take it to a guitar tech (or do it yourself if you're either amazing or incredibly stupid/cheap) get them to clamp it back together, and they can go from there if it is possible. if it does break, it is done. done. set neck after being broken off are unable to fix, but it all depends. take it to a tech.
it depends how bad it is. you actually might want to controllably crack the neck more so that you can fill it with glue. (Ive heard that this will actually make your guitar stronger)

if it gets worse and breaks the fingerboard, you are probably going to need a new neck.
Unfortunatly a new set neck will cost more than a new guitar. So if your lucky you can find a shop to fix it for you. Sounds like your cousin should be saving some money.
I would take it to a local luthier, and see if it's worth getting fixed. If it costs too much, it's probably time to start saving. A good luthier can do a lot though, you would be amazed at some of the repairs that can be done.
"The fool doth think he is wise, but the wiseman knows himself to be a fool." - W.S.
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that would be my advice too
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Yeah a really good luthier can fix just about ANYTHING. The problem is finding one. Don't go to a guitar center or some chain like that. Look in the phone book, newspapers, online, anywhere you can, find all the luthiers in your neighborhood, and ask them to show you some of the repairs they've made.
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