I was thinking of making some home-brew sparkling wine, only in a keg.
Here is my plan so far:

Purchase kegging equipment and several 3 gallon corney kegs
get a decent rose wine kit
ferment the kit as recommended, only adding sugar to get it to about
12-15% ABV if needed.
Add some acid blend to get a little more bite.
After 2 months in secondary, stabelize and fine.
After 1-2 more months, rack and add sugar to taste. Transfer into
several 3 gallon kegs and refrigerate. Purge keg with CO2 when filling

Now the questions: some say that corney kegs are rated at about 60 psi.
The guy at my LHS said that champaign should be carbonated to about
90. Beer is in the range of 12-15.

Would 45-50 psi work well for a good sparkeling wine instead of the
aforementioned 90?
Will the normal equipment for kegging work with the higher pressures?
Will the higher acid in champaign harm the stainless keg?
Anyone have and any other good tips?

Thanks in advance!

Alex Brewer.