That is most definitely incorrect. If his original damage type is fire and he does x damage, then taking a feat that allows him to do, say, lightning damage does "x fire and lightning damage", not "x fire damage and x lightning damage". You're adding a damage type, not adding damage. It means that the damage from his attack does both types simultaneously, so an enemy has to be resistant to both to resist the damage at all.
I'm also not sure where the strength mod or the 1/2 HD come from (not sure what HD refers to, actually). Does he have some kind of feat that gives that to him?
You're quite right. But there are a few more things to clear up. First of all: The way it's wiritten it can be argued that the feats REPLACE the damage type. And you only get to pick ONE modifier. So yes. This is cheating in the way of stacking things that should actually replace eachother or be a choice rather than a package.
Far as I am aware anyway.
You ever punched a polarbear for making you miss the buss? It's fun.