Usually the Geartronic boxes are pretty solid (assuming they've had their fluid changed at reasonable intervals, and haven't been abused). If, however this one hasn't been looked after they can be problematic and expensive to repair... I've seen the Geartronic boxes still going strong at 200k+
As for the ABS fault, it's common on this platform for the reluctor rings to go brittle and break apart on the driveshaft.
Re the AWD systems... They have a common weak point, which is the splined collar that couples the gearbox output to the angle gear likes to strip. However, I think this is only an issue on the R due to them not being built to handle the power! Change your Haldex/AOC fluid and you'll be dandy I reckon.
Here's a handy thread with a bunch of servicing tips for the R (same drivetrain as an XC70.)
https://www.matthewsvolvosite.com/fo...30306&p=138100