The info was actually in the service manual, which I definitely recommend picking up if you plan to do a lot of work to your car. It's one of the best written manuals I've ever seen and does a really good job of not just telling you how to assemble and disassemble things, but also how the systems work to begin with.
As for speakers, they are basically all Kicker at this point, though mostly because they were some of the few I could find that fit under the stock covers. I had to cut up the tweeters and bend some sheet metal to make brackets for them, but not sure if Kicker even still sells them. They were 3/4" and had a screw hole in the back for mounting, which was the biggest thing I was looking for. Doors are Kicker 6.5" (not 6.75", it's a 3 bolt pattern instead of a 4). I think they were the CS series, though I might go with something that didn't have the tweeter built in like the KS if I were to do it again. I actually clipped the wires to the tweeters on them, soldered them back on later, and I think I clipped them a second time. Rear speakers behind the seats I went with stock because I found them online for cheap. I believe they are 3" or 3.5" or something like that. I have heard of others going aftermarket here with a little bit of fiddling, but it's an odd size that I had a hard time finding much of. Sub is a Kicker 6.75" Comp RT. I believe I got the 2 ohm version, but I'm not actually sure if that's the right fit for the factory setup or not. The more I dug into that, the more I think the factory forgot to update the schematics. They show it being a dual voice coil speaker and there are 4 wires going to it from the amp, but on the actual speaker side of the plug there are only 2. So I don't actually know if the amp has two full channels for it or whether they are shared and just parallel output. Long story short, at the moment I'm running it as a single 4 ohm by running the coils in series. I'm tempted to try getting the 4 ohm DVC version and hooking both coils up to each channel of the amp, but I don't want to hurt anything and I'm not sure it would really make a difference in the long run.
All that said, I'm actually very happy with the way it sounds now. Has good volume and reasonable clarity for my ears at least, though it's always a losing fight to my exhaust. Before I often had a hard time making out vocals on the highway, now I can actually hear them if I turn it up and it doesn't just sound like noise. Seems decently powerful just sitting in the garage with the engine off as well, though not professional amazing sound system kind of stuff by any means.