[Aerich]

I understand that the XP awarded (for monsters, at least) is somewhat modified by character level. How does it work? Is it based on average party level? Total character levels?

Would it be best to have 6 characters from the very beginning (not really necessary, I've found, at least up to the Palisades fight, which is where I am), or to have around 4, then add a couple characters in later? Or is it better to stay with 4 (considering I will take a bit of an XP/level hit for class and race selection)?

I rolled up and started a new 4-player party (because I sort of messed up ability point and skill selections with my party of 6), and I was wondering if I should add more, and if so, when?

This powergamey party is lvl 2-3:

Paladin[2]/Monk[x] - drow, high dex, high cha, high wis
Ranger[1]/Rogue[x] - tiefling, max dex, rest evenly spread in int, cha, str
Fighter[4]/Battleguard of Tempus[x] - dwarf, max str and con, good wis - nerfed cha, so I won't be turning undead, even if I attempt to
Wizard[x] - elf, max int, good cha (for conversation), good dex, a bit of extra con.

Proposed additions (if at all, I'll see how tough the game is) would be a druid and possibly a fighter or barbarian tank.