I haven't really read all of these topics yet, but it's kind of interesting, and I do have some RPG Maker experience.
It's probably good to make TP something different than the default. Otherwise, it's just different coloured MP. Djinn's idea is good. Anything to make a battle system more interesting is good.
I'm not sure what scripts you plan on using, or what you've already got planned, but I find a turn order display incredibly helpful in an RPG.
Anyway, just throwing an idea out that I always wanted to use, but never really got working right. I like Wild Arms FP. I also like that it is a resource shared by the party. I must have seen this battle system somewhere before, but back when I was messing around with making a VX game, I wanted there to be two resources. I'll go over it now, just for the sake of it.
MP, which had your normal skills, which were less powerful, and Elemental Skills, which used points taken from a global resource.
A fight started out with an equal amount of all elemental points available. There were four - Fire, Water, Wind, and Darkness. Most attacks used only one of these, but some could use multiple. At the end of every turn, every element would increase a small amount. (Let's say the fight started out with 20 in each element, and the end of each turn, it increased by 5 or so). In addition, using an attack would cause the next element in line to increase by half. For example, using a 20 Cost Fire attack would increase Water by 10.
These points were shared by both you and the enemies. You could select to use the move even if not enough points were available at the time - if enough were created by the time your turn came up, then the move would be executed. Otherwise it would fail.
The point is, combined with being able to see whose turns were coming up, it was interesting to plan ahead. In addition, it let me come up with some neat skill ideas, and balance weaker skills in a way that might make them useful. (I had one skill that used a lot of one element and spread it out to the others, for example.)
I've never been a master scripter, so I did this mostly with in battle stuff. It did work, though it needed a lot of fine tuning (IE: Showing the amount of elements available on the screen, probably with pictures).
Honestly, the game never got far at all, and a lot of the skills didn't work, but I really liked the idea of it. Enemy scripting was a problem here, too. It wasn't impossible, but it took quite a bit of effort. That being said, if you know the fact that "This enemy has a really dangerous Black attack" then you would try to limit the amount of Black available. At least, that was the idea.
Anyway, I kind of went off on a tangent. But from what I've seen VX lets you do a fair bit of unique stuff. Even something like Lufia IP can make a battle system a lot more interesting. Anyway, I'll probably be reading through the rest of these topics in a bit. Probably post a bit more.
I've messed with RPG Maker a fair bit over the years, but I've run into two problems
1 - The game is in progress for too long, and I would come up with a "cool new idea" that I wanted to put in. This happens a lot. Then my games plot became a complete mess.
2 - Lack of motivation. This goes off and on to be honest, but unlike a game hack, an RPG Maker game can basically be endless. Which is scary!
Anyway, it looks like you guys are planning a lot better than I ever was, which is definitely the right way to go about it!
As a side note, my mess of a plot in my RPG Maker 2000 game is why my FF6 hack has a joke plot, and the Fire Emblem one is like it too. (Not saying the RPG Maker game didn't have a sense of humor, but it tried, and failed, to be serious.)