1. You can reroll for more stats to give them on creation.
2/3/4:
When you reclass, all bonus stats given at creation are typically lost. There are special re-class options, that might let you keep the bonus stats? I'm not sure.
For example, if you get a Thief's Dagger, you can equip it in a Thief's hands and have them "Use" it. The dagger will be consumed and they'll become an Assassin, circumventing the Stat/Alignment requirements. I forget if you also keep bonus stats from creation. (There are a lot of items with hidden uses like this. Some of them positive, some detrimental. Cursed equipment usually has functions like this, but are usually negative as trade-offs for getting rid of them on the spot.)
The things you keep are HP pool, spells learned, and spell pool. So, it's possible to get someone to 9-spell pool in all levels of a type of magic, plus learned all its spells. Then transition them to a different class with better health/equipment-access than the magic class and they'll keep all their spells.
Unlikely, the class has shown up in his previous games and they never got stuff like that. If you want something silly, I recommend Bard. Bard is somehow the most broken class in the game in the demos. (Dunno if that'll change in the full game.) Which just makes them funnier.
Seriously, when someone ports the Male Bards mod from earlier demos (Bard is normally female-only), then you can just have everyone dual-wield Sleigh Bells and infinitely stunlock entire groups of 30+ enemies at once while also doing lots of ice damage to them. It's actually the most effective party build anyone came up with in the demos. It's really funny.
