I agree with Biggles Wader. If the seller is a reader of this forum and reads a post that says you have made a bid that you don't expect to be accepted then you had no chance. You should have posted that a friend of yours just bought the same boat for £48k and that you had no intention of...
Mine has a one inch diameter bar that you shove through it to take the weight when it is raised.
Regarding the choice of lift or twin keels, there are pros and cons, as with everything.
Could they buy a few extension kits? They seem to consist of just a foil, liner, joint and rivets.
As in here http://www.riggingandhardware.com/p-46383-schaefer-2100-10-6-extrusion-extension-kit.aspx
No idea about UK suppliers.
Just remember that a wet dog is considerably heavier than a dry one. I could barely lift my old labradoodle back into the boat when he fell overboard (which he did a lot). This time I've got a miniature one!
"Massive" in terms of engine power, not physical size. I have read that tests showed them dumping two gallons of fuel an hour into the water. In the sea that might be a drop in the ocean but in a lake, however big, it's totally unacceptable. (I'm not arguing about whether that figure is true but...
If you don't like 4 strokes then blame the jet skiers. It is they who insisted on using massive two stroke engines in America's freshwater lakes, with with half their fuel, gallons a day, going unburned straight into the lakes. That is what I understand started the two strokes bad, four strokes...