Where I can just punch in the level I want to be? Leveling is VERY tiresome in this game.

And does that infinite experience from trias really work? I tried it and nothing happened.

I've tried it different ways and still nothing happens.

None that I know of.

Given how the game was made, you practically have no need for leveling by farming monsters or similars (btw, I find it despicable in all the rpg games really - they are meant to be played not to be farmed). The first time I finished the game I was like level 15 or something like that (played very badly) but didn't have any big problems in finishing it. If you find an encounter to be too much for you, avoid it by dialogue or running - it's written nowhere that you should win all combats in a game.

Having a high wisdom, however, helps.

The devs disabled the debug console before release. There *is* a mod out there somewhere that partially restores it (hosted at Sorcerer's Place, I believe). You might want to check out the PS:T mods at Spellhold Studios as well.

You need high levels to get that aegis ring.

the Tome o' Cheats from http://www.spellholdstudios.net/ie/pst-qtweaks
will give xp

Are you sure? Because as far as I know, CLUA was disabled completely in exe unlike in Baldur's Gate. Like they stripped out the init sequence. There are still remnants if you are looking at UI interface in Near Infinity as well as in exe but I have never been able to get it working. Nor have I see anything that re-enables it. Maybe you're thinking of trainers? Those are not debug console...