Glad to see you're open minded.
You actually don't have to be a good sniper or anything to dominate on the map really. Spamming arrows with the huntsman, or rockets/stickies (basically anything) is extremely effective in itself. You don't actually have to see anything ether, just spam, spam, spam, and you're sure to hit something. That's the no strategy part I was talking about. Snipers just get the most advantage because they’re at the safest distance away.
Sniper bots do work well at detecting bad sight lines. This is because they always go for the longest view distances they can find, but only if they actually leave the spawn room!

hmy: There's a bug that sometimes makes them get stuck in the spawn and I think they were getting stuck in your map. One way to fix this is to mark sniper spots on the nav mesh, but that's a more advanced thing all together which you can read more about over
here if you like.
The texture problem is a common first mistake. Typing “tf” in the keywords box of the texture browser will filter out non tf2 related textures.
Like snark said, I can understand the desire for a simple intense fun map, and It can be easily done in a game like Counter-Strike because every player shares the same abilities, but the problem with tf2 is that every class is very unique and different from each other and this makes it extremely hard to satisfy every play style within such a simple map so you usually end up alienating most players by favoring one class over all others. Now you're also not the first person to try this ether for TF2 and most have failed at it. ctf_turbine seems to be the only map that's ever really succeeded at it and probably by accident.
In any case koth is probably the best game mode to start with in TF2 mapping because it's the easiest to balance, but still requires more work then most other games do to get right. All in all it's not the worst first try I've seen at a tf2 map. Heck, I've fooled around in the source SDK for years and have made my share of crappy maps. Just never released them.
There's also a ton of helpful tutorials here on this site alone too that can help you improve your skills greatly so I would differently look around. Good luck with you future projects!