If I were to go ahead and get the hazmat endorsement (and perhaps the tankers as well), could this open up for more opportunities after graduating truckdriving class? Or would no one want to hire and train a new driver hauling hazardous materials of any kind?

I already have my Class A's, I just never went over the road afterwards (I'm not sure if you can attain a hazmat with a learners permit), but I'm considering going through school again and going over the road this time.

Any endorsement is a feather in your bonnet. The hazmat endorsement goes hand in hand with the tanker endorsement. Hazmat used to be a hiring requirement for most larger companies out there. The larger companies just gave up and in my opinion if you have the endorsement running for one of the general freight outfits, its a waste and you're more apt to pull freight that your company is making more to pull for the same meager wages as the other drivers. I prefer tankers and hazmat over all other freight types. It is always better to have the endorsement and no need it... that need it for some opportunity and not have it. If a good job arises and you don't have the endorsements.. you have to get in line and wait while others get the job. Just know that there is much more to hauling hazardous materials than just having the endorsement.. there are far too many driver hauling things without a clue on what they are doing.. don't be one of those guys!

Pick up any endorsement you can, most will train you. Lots of places want Hazmat and Doubles/Triples endorsements and are willing to train you on driving those. Same with grabbing Tanker while your at it with Hazmat. Everybody had to be trained at some point in driving those, no veteran driver pulling a tanker or D/T got there without training as a newbie to it.