I'm buying a HobbyMat MD65

Hi Stuart,
Yes it is a good lathe. It has limitations, but they all do. If it comes with all its original bits it is a versatile bit of kit.
Not really. BUT if you intend to turn stainless steel over about 25mm diameter the slow speed kit is a good idea. Slow speed kit gives 75 rpm as opposed to the standard 250 rpm minimum speed.
None needed, the lathe comes with change wheels which give most common pitches of threads.
Yes if you mean the tappings in the bed plate. But the column mounting comes with the mill head not the lathe. The lathe does come with an angle plate, vice and tee slotted table which means that light milling is quite possible.
As far as spares go Essel Engineering still carry a full range of reasonably priced spares and accessories.
Find a copy of the original advert which lists all the bits it should have, if any are missing get the price reduced.
Regards Colin Docherty