The concept of summoning in battle is not confined to FF. For instance, you can summon in many fighting games. The same goes for "LIMIT breaks". Go for it. It's all in the mix.

As long as you balance the effects of status on weapons and magic, you should be fine. Status affecting magic/weapons could fair poorly if it compounds a person's suffering. (The same could be said of compounding rewards, but it's sometimes hard to wipe off the grins in those cases.)

For instance, having very little health is fine. Having a spell or weapon fail is fine. However, having your poor health destroy your spells and weapons would be a pain. There could quite possibly be very little you could do to heal yourself without the magic and weapons. (You could probably design around this example, but hopefully you see my point.)

Names of classes are always okay unless the audience is picky. What counts is how you balance them and make them different from each other. If you are speaking of what may be the standard "Knight, Thief, Mage", those classes may be cliche but they have often succeeded in gameplay.

you got to remeber a game that is easly beat gets boring. Take all these dbz games you can walk in and beat the main boss with a little help from a expert on the game. But like dwo witch takes time and even at the max lvl its hard to beat the boss do all of thoughs would help keep the player intrested.