greatweapon+brace of handguns

A character with brace of handguns and a mundane greatweapon can choose to attack with +2 strength(GW) or +1 attack(2 handweapons/pistols) right?

Yes. As long as none of his taken options are a Magical CC weapon he can choose which of his options he uses in CC. Some characters(none Ogre) can take a ranged magical weapon. They too can use whatever CC options they can mesh together.

Brusier/Tyrant could take GW, BoH, Ironfist and use whichever best works for that combat. Just remember that whatever he starts each combat with, he is stuck with until that combat ends, even if it starts turn 2 and ends turn 6. You can't, for example, charge with a GW and then in the second round of combat switch to an Ironfist so you don't strike last. You would be stuck with the GW.

You can't have Ironfist and a great weapon. It says "either a great weapon, an additional hand weapon" and so on. Brace of handguns is a exception because it says "may also have a brace of handguns".

BOH and GW with the Beast Killer big name (ItP & d2 wounds on large creatures) could be a good cheap option.
HA, luck gnoblar and Wyrdstone as well.

Its hard to give up my Tenderiser though

"or" is not always exclusive in English. In this case though it is used as such and we can tell so by one of the later options using the "and/or" wording. So, yeah I guess you can't have certain options together.

thanks everyone, that's good news.

But yeah, hard to drop the tenderizer...

you can still take the brace with the tenderiser - and shoot or even stand-and-shoot with them, but not use them in combat (unless you lose your tenderiser through a vaul's unmaking or similar effect)