Power leveling

[Eroge]

I notice a lot of people asking for plvls, or being power leveled by one of their friends. I don't know the rules behind it so I never dared to ask any of my higher leveled friends if they'd power level me.

1) Is it legal to ask, be offered, or get power leveled? What about if it's just yourself Plvling your own alt character on 2 computers? (People told me you can level up an alt character real fast depending on how high your main is)

2) How does plvling work exactly? I notice it's different in many games. Like on Flyff, you get no exp if the monster is 19 levels higher than you. (or something like that) So if I was level 70 and wanted to plvl a level 20, would I want to be killing level 20,25,30,40,50,60,70, or even level 75 monsters for best exp? In games like Knight Online, you get more exp when plvling people half your level for some reason...@.@

In all games I'm never lucky enough to get power leveled. I'm always the sucker doing it for others because I have a hard time saying no.

3) I'm not that high of a level so I was wondering what it's like levels 80+. Do you high leveled people even get plvled anymore by lvl90-100 players, or is it better to just party with players your level and grind Yellow/Red mobs?