Pickups?

(man its been forever since ive been on here, anyways)

I have an Epiphone les paul standard and a Pod X3 Live, I have found when i play through it in Hi-Gain/Hi-volume situation when i mute my string to stop playing i get a VERY annoying squeel. While i was getting lessons from a guy a guy whos been playing guitar for like 20 years he atrributed it to the closed pickup that i have, and demonstrated by playing an old open humbucker explorer looking thing that wasnt a gibson (a mach one something) trough the same pod and amp on the same settings he didnt get the squeel, now my questions are:

Im shopping for pickups, i need something under 200 dollars, and i dont really want to push close to it, whats good for metal/heavy rock in this price range?

If i have to only buy one pickup, (very likely, i would like a good one) that would mean i would need to buy a passive humbucker right? i dont even understand the passive/active thing right now and ive read you shouldnt mix them.

And with that comes, what exactly IS the difference between passive and active humbuckers?

Ok, sorry if this is very confusing, im very confused right now myself, so......yeah.

Edit: Oh and, whats the usual price for getting a pickup switched out? I dont know if its a roject someone who has very little experiece in guitar construction should undertake.

Looking For A New Amp

OK, im gooing shopping for a new amp saturday. im looking to spend around 300-400 dollars, is there any amp in that price range that would be Ok for gigging in like small clubs and jamming wiht a band (which im deffinitely not ready for anyway, im just going to have the money now and not later, bc of job availability and school.) im going to be playing heaviER stuff, but not like Hardcore or anything, i like Marshall amps sound, but idk if their are any giggable in that price range.. a little help (oh and i dont know how amps and ohms and stuff work, could anybody give me an idea of how many i would need for gigging/jamming? that might help a little
sorry if i didnt provide enough details/this is a really noob question.
Edit: oh and on the Marsall in my avatar the overdrive channel doesnt work, thats why i cant use it.

Dream Theater

I love progressive stuff, therefore i love Dream Theater, sooooo, im going to be getting paid this summer which means new CD's (and an Acoustic) for me, i really want another DT album, so which one shoud i get? I have Awake (old album) and Systematic Chaos (Newest album) already (i am a kinda new DT fan, just startedd listening to the last year) I enjoy both albums thouroughly so i dont know what to get, their older stuff or the newer stuff, can i get some help from people who have heard them?

Day Jobs?

Just a random question.
My dad is a personal airplane mechanic (on planes that carry like a maximum of 10 people)
So i get to work up at a small airport pulling airplane engine parts out of acid taks and cleaning them, its pretty cool for a summer job while schol is out.
So what do you guys do?

Coheed & Cambria

I personally think they are the best Non-Metal band around right now (some people consider some of their stuff metal i dont, its not particularly heavy, its much more Prog than anything, with exceptions from their newr stuff).
Their new album that came out this year Good Appolo Im Burning Star IV, Volume II: No World For Tommorrow is one of my top Favorites (along with their other 3)
All of their lyrics are based off of a story written by the lead singer/guitarist which is being displayed through a comic book (The Amory Wars) (some of their lyrics are very strange, and the story is why)

http://youtube.com/watch?v=kKCpFvRrk30
If youve never heard of them, heres a link to my favorite song by them, Gravemakers & Gunslingers.