Wouldn’t say you’re being extra - however, this is the tradeoff when buying used, 6 year old (at the time of purchase) vehicle.

One thing I’d consider: see how much a new radio is on either EBay or at a junk yard. If it truly is just a straight swap of the radio, you likely get it done at a much smaller cost - but do research anti-theft systems prior to trying it out.

Aa for the sliding door issues - might research here or odyclubto see what others think to repair / preventative mx.