For build, something like this is what I used to use as frost:
https://wotlk.evowow.com/?talent#jbh...uzAZf0M:kN0zVM
Basic playstyle is too pool RP and unleash hell with frost strike spam. In arena, a very basic gameplan can go something like grip + strang + trap + fear/hoj/cyclone/hex from your healer on opposing healer and then ams to avoid cc/ibf to avoid stuns and kill the enemy dps when your trinket procs under unbreakable armor.
There's not really a concrete build on what you absolutely need to use, you can change talents on what you need/preference, but try getting Scent of Blood, full on Chill of the Grave and at least 4/5 Killing Machine. I really liked the reduced grip for more freedom on grip for interrupts and peels, but you can easily max scent or put pts into icy reach, w/e really. howling is not worth taking in 2s, it's fine in bgs. Deathchill can also be an optional talent if you don't find yourself using it enough or needing it for the kill. For glyphs, frost strike and hc are a must; 3rd can be any utility, chains of ice adds good damage for your chain spams, ams is awesome to go rambo or against shatterplay/rp, strang is situational, and also obliterate if you find yourself using it a lot (you usually wouldn't), disease in 1v1 can also be good for squeezing more death strikes.
As for weapons, it's up to preference tbh, but to me pve weps and gemming more resi is the way to go because of the higher weapon damage.. even though agi is a mediocre stat, it should be better because of the higher base dmg you get from frost strike.
Overall it's a fun spec for sure. Slightly less "depth" than UH, but has its place and you can totally play it. Just keep in mind that good players are aware of what it does and you can get spam dispelled and/or kited/disarmed and lose all your damage much faster than uh since you depend more on melee range.