Oh glory. That tank is right scuzzy. The tetras you have look surprisingly ok...In case I missed the post on them, they're black skirts, and maybe a white skirt in there.
Yeah, that's gonna be work. lol You'd be surprised how things clean up though. Work yes, but probably not as bad as you think after looking at it. Scrub the windows good, vacuum. If you go slow it'll probably a week or two to actually look good again, but it should start looking better faster than you think.
As for your medicines and stuff you got, yeah, the PH tester good, aquarium salt always good to have on hand, I know nadda on the rest so I'd go with Romad's advice on just about everything, looks like he has you covered. lol That'll be a gorgeous tank once you have it fixed up. Mine started out similar, except without the water and fish, which I suppose made it easier(they drained it for me and I bought no fish, they did, however, leave it with the same water and dead fish for a couple years before selling it to me....ugh, I was washing fish bits off the windows), they also broke the cabinet on the stand and it has this stain, like someone dumped a soda on it and left it there and I can't get it off. x.x Bits of water stains on the lid and lights too...but it looks good, yeah? Hopefully it'll make a nice example, though I'm no awesome decorator or anything. lol
This is how mine looks now: