D&D 3E

I was reading my 3.0 PHB and I came across a couple of things that I need some "plain english" translations for.

First of which is the following, "+2 Bonus on Opposed Attack Rolls". I think this means a +2 bonus when attacking someone with this weapon (Flails). Please confirm or correct.

Second, "A creature using a double weapon in one hand, such as an ogre using a dire flail, can't use it as a double weapon". I am not honestly sure on this one.

Thanks in advance for all help,
Quartermane

3.0 not 3.5 because i refuse to buy more books. doesn't really make much of a difference for this question anyway.

i'm dm'ing a game where the players are all genasi as described in the FR book, although i'm probably going to modify the races to better fit my campaign. it's an elemental based campaign. anyway, i'm thinking of creating a set of feats the characters can take that are based on elemental powers. if the characters choose to expand their connection with the elemental plane they're affected by, they get some more powers. but i want to keep the feats balanced and not make them like, super powers. i'm fishing for suggestions for appropriate feats. anybody got any?