i don't personal punch things anymore, i prefer the open hand and the hammerfist... and of course the elbows, i strike my utility pole with them, not too hard though, but hard enough(alot harder than if i would use them to hit someone)... i am also a fan of the headbutt, i watched my goat when he did them... the head would sink into the slight rising of the shoulder for stability and then... WANG!! hence his name.
i agree entirely about smashing up the hands after years of hard training, that's why i stopped punching and switched to other fists.
cinder blocks are good for low push ups, just stick them on end... or you could just put your feet on the upended side and do push ups in this fashion.
push ups with your kids on your back are good... until they get bigger anyways.