Hey all you bricksters out there!

I need some advice on urethane bushings. I live in australia, and if you haven't heard our roads/potholes are generally on the worse side of really bloody bad. My question is about the rear of my NA non irs 740 sedan. Basically the rear end seems to bang around alot, causing an almost "wave" of vibration through the car at every big hole. This is quite annoying, as the gearstick also goes mental (i.e. the gear box is bouncing round a fair bit - possibly due to it's mount???), and i hit on average about 50-60 of these every day(just a wild guess, but it DEFINATELY isn't far off it! Thats an idea of how bad the roads are in my area, i drive 12 kilometers and hit 50-60 of them! I only hit the ones i can't avoid!). The vibration annoys the heck out of me........I remember reading somewhere that you can get urethane bushes for everything in the rear, and that you have to drill the old volvo ones out, but that installing the urethane ones is a piece of cake (ie. no special tools needed).....Would this fix my problem? Would this cause something in the rear to be overstressed and risk breaking if i hit a huge hole (blown a tire or two already in only 2 years)?????

One last question, the front end of my car bangs quite badly when i hit a small-->big bad bump. The sound is very metally and almost sounds like an almost metal to metal contact in the top of the strut towers, (but not quite a complete hit!). The suspension place that did my fron suspension refuses to admit that it is anything more than the "Top Hats", (i.e the bearing device in the top of the strut tower), is this right? I KNOW it shouldn't bang, BUT, i don't/haven't had the time to get a second opinion. Which is quite annoying......the banging is giving me the poos. Anyone else had a similar experience? (the rubber bushings at the end (tire end) of the control arms was replaced with urethane bushings, could this be a problem too?)

THANK YOU ALL!!! (In advance!)