TP, EP and PP (their importance and when to use them), also, stats distribution?

Some of these answers depend on if you're just going to play through the game once, or if you're going to play twice (once for "fun" and once for the True End).... and if you're playing twice, whether both cycles will be at the same difficulty or changing in between.

TP: Early in the game, you can trade 25 TP for a Vessel of Life, and then sell it for a nice chunk of cash. That would solve that particular issue if you need it to. Otherwise, crafting manuals of all sorts are generally good purchases, though some of them might not be useful early on since you won't have the necessary ingredients to do the alchemy. Some of the equipment might be helpful at times, but that comes down to your party and judgment.

EP: So long as you're not looking to trade equipment on your main party anytime soon, it is helpful to upgrade their equipment.... especially for the AP bonus at higher equipment levels. Equipment that can be upgraded and converted into passive skills is also nice to have.

PP: If you're only going to play one cycle, feel free to spend it as you earn it.... although spending it on the hero might not be the wisest idea given you lose one at the end of a generation. There's some logic into piling it all onto one guy, to make him (or her) uber-powerful, but there's also a valid argument for spreading it out among your team. The only thing I'd advise is not to spend it on someone you're not sure you'll keep in your main party of six, as that becomes a waste once they're not in use.

Stats: I'd suggest piling it all into the primary stat for your party of six. Fighters should focus very heavily on STR (for ATK and HIT), while mage-types should put the lion's share into INT (for MAG). You can filter a few points into AGI (turn-order, mostly, but also HIT), and some into VIT (for DEF) if you'd like, but they're not quite as important. As your guys level up, the other attributes will get some points from the randomly distributed stuff you have no control over, so it isn't like they'll be completely inept in that area (but it doesn't really matter if they are).