The measurements for the 280

Actual footprint is 1150 x 460

Overall length is 1200 and overall depth from the to rear of the splashback is 800

Height to the top of the headstock is 1200

There are a couple of different base styles across the range which might effect the measurements and. I think (but don't quote me) the 280 is the same length as the 10-20 and 11-20 with the 10-30 and 11-30 being 10 inches longer.

There is no definitive answer to that question.

In my limited experience, price depends on age, condition, ancilliary equipment, your ability (or not) to collect and luck.

The one I mentioned in your previous thread sold today on ebay for £1900, which was a steal. I have seen them on ebay for even less though one dealer on there is currently asking over £6K for one. I think if you are prepared to wait for the right one, prepared to travel and have the wherewithall to collect yourself, you could get change from £2K. If you can't collect or arrange collection yourself, you will tend to be at the mercy of the dealers and the price will likely be higher.