The only difference between the two is that PCB mount has two additional plastic legs for better alignment on a PCB. Either type is compatible with Keebio PCBs, and if given the choice, PCB mount is preferable to keep switches aligned better.
Depends on the type of hotswap socket. Here's some info on each type:
- Holtites: Not recommended, they suck, use them if you want to have a bad time
- Mill-Max: We use the 7305 and 0305 Mill-Max sockets for our hotswap boards, and they work well.
- Also check the Mill-Max Switch Compatibility Chart for the switches you'd like to use
- Outemu sockets: Yes, but they only fit Outemu switches or Pandas
- Kailh hotswap sockets: No, PCBs have to specifically be designed for them, and typically, if it was designed to use Kailh hotswap sockets, they will already be pre-installed. See the image below that shows the parts that can't fit onto the PCB.