ding ding ding. I still have the original cart that I got for christmas the year it came out. I've replayed that game sooo many times. It's been awhile, I think it's due for another spin.
You'd be surprised. I always try to test my strategies against myself so I'll play with a friend and direct him on how to set up the defenses and then we'll skirmish to see if I can get through.
It's hard on the armor path, but not impossible. On Infantry the ability to use off-map arty makes it damned near impossibly easy.
The overwhelming force on a bridgehead defense isn't shabby by any means, but it can be broken. The beauty of it is to cause so many casualties that you can hold them at a second line. Problem is, most people don't bother setting up effective second lines.
I really really wish you could blow buildings directionally to block roads that they either have to send engineers up to blow through or use a tank with a bulldozer attachment. It'd make real defensive works a lot more interesting.