I don’t know if it’s possible to lower the Breva significantly in the rear end. I think not other than reducing the pre load and operating the shock closer to its compressed limit on the damper rod.
Lowering the bike will always make it sit straighter on the side stand and harder to some degree to get on the centrestand, there are ways to mitigate the problem on the centre stand issue.
I have posted several times, the service schedule that catches every conceivable issue that you will face.
These bikes are notorious for poor greasing at the factory, but not hard to remedy if you want to.
The issues and fixes are well documented on these pages.
The 1100 2 valve motor is very much a known quantity and has the reputation of being a virtual rock of Gibraltar reliability and longevity wise, there are no known deal breaker type issues with them.
Suffice to say on the CARC integrity issue, the straighter you can get the drive shaft to the gearbox output shaft, the less work the UJ has to do, therefore the more trouble free you can expect it to perform.