2002 Grand Prix GT Car Shakes/ Brakes

Hey, I have a few questions:

My car is a 2002 Grand Prix Gt - 17" aluminum wheels with the BF Goodrich stock tires. ~114 000 km (71 000 miles) in about 2 years (yeah I drive a lot).

1) Anyone experiencing wheel or car shakes at about 120 km/hr (75 m/hr)? I am going to get a wheel balance / alignment done again - I had one done at 90 000 km.

2)Anyone having brake problems with there 2002 Grand Prix GT? I recently replaced the front pads and discs and it looks like I have to replace the back pads and discs. I want to get some brakes that are more suited to high mileage driving. I drive about a 1000 km/week (600 miles/weeK) and it is a lot of highway and useless rush hour driving. I looked at the GM Auto Parts site that was suggested on another post - any other thoughts?

3) I also have to get a coolant flush and fill - thoughts on going with DexCool?

4) And it looks like I need a transmission flush and fill. I read alll the posts about getting one and everyone seems divided on the topic. Anyone experience any problems recently with the transmission flush and fill?

Thanks for your help!

It is possible that the problem is with wheel and tire balance so your plan to have them balanced and an alignment is a good idea. However, if that does not solve the problem check the axle shafts as you may have a CV joint going bad. They often start indicating a problem when you are running at speed and then they get worse as time goes by and they wear further.
As far as the brakes are concerned get a good set of aftermarket rotors. Raybestos are reasonably priced and available at most autoparts stores. There is nothing wrong with GM rotors although they are somewhat expensive. As far as pads go I like Raybestos with DH3a or Performance Friction Carbon Metallics. You can find these at Autozone or other autoparts stores or online.
A coolant flush and fill is a good idea but if your car does not have Dexcool stay away from it. There are a lot of problems with Dexcool clogging up systems and not living up to the claims. Most folks on this forum are flushing out the dexcool and putting in the old green antifreeze because of the problems they have had with the Dexcool. Prestone has a new longlife coolant that claims to work with all systems. No real information on this as of yet.
Finally, as far as the transmission flush, DON'T DO IT! A fluid and filter change will give you good results. Everyone I have read about that had a tranny flush ended up with a tranny replacement within a couple of months especially with high mileage cars. It seems that the flush dislodges particles from the clutch disks and bands that destroys the transmission. I have never had it done and do not intend to. Hope this helps!

I agree with GTP 100%. The problem with a trans flush on a high mileage car is that new fluid is "grippier" than old fluid, and can sheer the clutch friction material from the backing plates causing catastophic trans failure. The amount of fluid exchanged during a trans filter swap is enough to give the fluid a needed increase in detergent content along with removing enough contaminants to keep things running smoothly without the shock effect of a complete flush. If the fluid is so burnt and nasty that a flush is recommended, then the damage is already done and your trans is toast, so save the cost of the trans flush, avoid the middle man, and get that trans rebuilt. ;)

Thanks a lot for your help. Off to the mechanic this week!