That is most based on how you want to play. Unarmed is a good first char tag to pick since it will allow you to stand a chance against weaker random encounter critters, that goes melee, and such weapons as knuckles och powerfist (i think) is counted towards unarmed.
Science and Repair skills are used mostly to be able to craft items, but most items have other skills needed at certain level as well, as the 10mm need 45% small gun skill to craft (i think).
I would say that some skills that seemed fairly useless in regular Fallout 2, have their uses in this game, whereas Gambling skill, seems to be completely useless.
Barter affects how much time you have going through traders inventory, as well as prices..
Speech i think affect how much time you have for common dialog, but those doesn't take to much time anyway.
that is what i can remeber offhand...