When you popped the hood, I noticed that the BPV has an open T-fitting, causing an air leak. There is supposed to be a vacuum line there going into the cabin to the boost gauge.

Dude this is a steal. This is why Subarus get such a bad rap. Because people like you buy them and have no idea what’s going on. You complain about plugs when all you have to do is take out the battery, window washer tank, and the intake and the plugs are very accessible. About a hour of labor for the less mechanically inclined. There’s an open T fitting on the bpv which is probably a root of your issue, along with plugs and coil packs won’t hurt either. I’d check on other vacuum lines too. Your battery has a draw because the switch on the steering column is on for the parking lights. These cars are extremely simple, and relatively cheap to fix. This car is cosmetically ok and all stock which is a huge bonus. Under 200k is a bonus too. The fact that you spent $2500 and are complaining is beyond me.

thats it?? thats honestly a really good deal

Are you sure the parking light switch is off? It’s located next to the boost gauge on top of the steering column. (Im pretty sure thats whats going on here, let me know if this helped, good luck.)

you admit to not knowing anything about subarus, and still you bought one. your tenacity is commendable, however your statement is not uncommon. these cars are considered special needs and require more knowledge than a honda civic or toyota in order to fully fix them. the "tail lights and marker light" are on because the lever on top of the steering wheel is switched on, and the misfire is almost certainly spark plug or coil related. in general I think you should research more before buying cars you're unfamiliar with