Simple Questions from new diver

[MNLakeDiver]

first welcome to MNscuba.

I am sorry I cannot speek to PADI requirments but I'm sure somone will soon.

I dive with mostly used gear. I checked with local diveshops to see what brands they are autherized to service. you can also check out the mfg. website for local dealers/service centers.
depending on the type of equipment and the price you may try to negoiate with the seller. I have bought equip. conditional on it passing an inspection that I pay for. If the equipment is good your ready to go if it is bad or needs alot of work you are out the cost of the service check but not the price of equipment.