Pomyboy wrote:I have just applied a chimera, and a squad of melta vets to my army. I have 2 heavy flamers on the chimera. Going for enemy battle tanks, should i drive strait at them and hope armor 12 doesnt fail, or would go a more flanking way?? Also when i disembark my vets out of the chimera, could i then use it as a kind of hellhound tank and pick the squad back up when they have finished their job, or just keep the tank with them??

You're missing the point.
If you're going Mech Guard, you should have so many Chimeras and Vet squads that you don't have to rely on AV12 to protect you. To be honest, AV12 isn't enough to charge anything more than small arms. A guy with a missile launcher, melta or a lascannon can slag AV12 no problem, and many armies have melta or missile launchers out the wazoo. The way to combat that is not to try to keep single vehicles alive, but to have so many targets that they can't bring you down quickly.
As for disembarking or not, don't disembark unless you really have to. Veteran squads are far too squishy to survive outside their Chimera, and should only get out if their transport is wrecked or they REALLY need to take their shot at the enemy.
And using a Chimera with 2 Heavy Flamer as a poor man's Hellhound isn't really the best. Just use a real Hellhound.