My BX-23 just turned two years old. When it was delivered it was a bit low on hydraulic oil. My dealer made a special trip over with a couple of quarts of Super UDT. As I recall, it took less than a quart to top up, so he left the remainder of that quart plus an extra quart with me just in case.
Yep, the published capacities are way off -- I think Kubota has trouble with Metric/US/Imperial conversions and gets them all confused! I just did my 300 hour oil change and, as always, it took 3.5 quarts. I'm running Mobile-1 "Truck and SUV" synthetic by the way. It started at -13 degrees last winter, so I'm sold on that stuff!
Regarding the dipstick, just tilt the seat forward and work from over the left side fender. Still not great, but better than trying to access from the rear.