here's my go at it:
Is a Mooney to much airplane for me? no.
How tricky are they to land? not at all.
How hard will it be to transition to? if ALL your prior time was in high wings, get ready to love low wings. otherwise, not hard at all.
How reliable are they? depends how well it was maintained, I guess.
How safe are they? as safe as you are.
How expensive to insure and maintain? I guess you have to shop around and get quotes, but if you have retract time and your IR, shouldn't be TOO painful to insure. mx is whatever it takes.
What do I need to know I have not even asked yet? be prepared for a good time.
Who would you get involved for a prebuy inspection ? I've only purchased one plane and I got a PPInspection done, however in the future I would have a hard time accepting anything other than a full annual as part of the deal.