if i buy those skills packs....need some quick answers..

http://wiki.guildwars.com/wiki/Skill_Unlock_Pack

let's say i bought the factions skill pack, will i have access too those instantly for use?

For PvP use you would yes.

For PvE they would be unlocked for your heroes but not available to use on your character without buying them with that character or using skill tomes.

To add to this, you do get them unlocked for your PvE character.......in a manner of speaking. You would just have to buy them at a skill merchant of select campaign area. You can also use tomes/elite tomes to obtain them on your PvE character.