[Radek]

1. The carrying capacity does depend on the race indirectly:

your carrying capacity = your weight times a factor which depends on your STR

Therefore, a pixie with STR 24 has considerably lower carrying capacity than a whiskah with STR 24. The factor is the same (about 1.5) but the weight of a pixie is much lower than the weight of a whiskah.

2. The priest. The problem isn't whether to have a priest in your party or not. The problem is whether to be able to cast Spirit and Vine spells or not. You should be able to cast Spirit and Vine spells at any rate. You will be unable to heal yourself without Spirit spells. You will be unable to cure poisoning and diseases without Vine spells. Take a priest if you do not plan a paladin and a ranger in your party.
As far as the fighting ability of a priest is concerned, I've never played a priest but:
- there is Battle Mace +2 in the game. If the priest is able to equip it (and he should be able), then the mace is a powerful weapon for him. A normal Battle Mace (not the +2 one) can be found in Asylum. Next normal Battle Mace is available near the Serpent Temple.
- the Heroic Might spell makes miracles with non fighters. Even a Mage will fight as a god under influence of this spell. The Heroic Might spell is a level 4 Spirit spell, therefore, the priest should become a valuable fighter very soon.