I know the remake has a lot of player colors already, but why not add some more? It should be easy to implement, since they're in the game, but only playable/accessable through the map editor. I know it might not seem a big thing, but player colors for me are a big deal

Though maybe some restrictions are neccessary, because a lot of colors are almost the same..
For multiplayer we must restrict the available colours because otherwise they will become too similar (e.g. you can't tell the difference between dark red and cherry red without looking closely). In multiplayer we want players to be distinguishable at a glance. The current colours is about the limit if we want to keep them very easily distinguishable, I have tried adding more but they always turned out too similar.
For singleplayer we don't need any restrictions, if the guy making the map wants to make two teams look similar, that's his choice. Currently the map editor only lets you choose colours from the original KaM colour palette, (for backwards compatibility of missions) but we can support any RGB colour. I imagine we'll go with HTML style hex colours (e.g. FF0000 = red) and a graphical colour picker, but it doesn't seem like a priority now. (especially when most of the editor features are incomplete)
Regarding a tower limit: I find I am repeating myself so I added it to the FAQ:
http://www.kamremake.com/faq/#towers
Based on several tries to conquer TSK mission 8 with legit play through, something has come upon my attention on that mission. A quarter of the time I make enough towers to fend off the initial waves, but after the enemy is held at bay I'm left with what, no stone? Seriously, of all of the two building resources, my stone goes in to my towers after the fight leaving me without enough to build a road to my stone cutter and it's building material requirement. I know I know, I should just tick off on each tower not to have stone delivered for a bit, but my serfs are already carting off the precious stone.
I didn't find this a problem in KaM TSK/TPR. If you used all your stone on the watch towers, then you probably made too many. Try building a few less towers and using your troops to defend behind the towers. Try building the towers at a different place, try making them more spread out or closer together. Experiment with tactics until you find a way that works well.
I think it is an added challenge to manage your stone supplies, if you build too many towers it will all be wasted. You might also like to turn off delivery of stone during the battle.
Increasing the stone supplies will just lessen the challenge/tactics. We might as well add 200 extra bread to every mission so that people don't have to worry about running out of food at the start. Managing resources is just one of the challenges of playing KaM.
Maybe the map needs more starting stone. With the next release, I've heard towers miss less often, lessening wasted stone. And another thing about towers is: why do two or three towers throw their stone at one enemy unit when only one is necessary? I could hear it now amongst recruits, "This one's mine!" or "I'm out, he's yours!"
That's pretty complicated to implement, it's hard to tell whether someone else is already throwing a rock at a target. Also I'm not sure the recruits would be that organised in the confusion of battle. But maybe we can add this eventually, because I agree it is frustrating when stone is wasted. This might actually make towers too powerful because in KaM they did this as well.