Do they have keyboards set out that I can try typing on? If so, how many? Hopefully both mechanical and some cheaper membrane ones?

The salespersons on the floor are very helpful and if you want to test a keyboard on one of the display computers or your own laptop, I'm sure they can accommodate you. Just ask

There are some on display that can be touched/tested upon, but most are not connected to a computer of you're looking for that level of testing.

A lot of variety and staff that will definitely shed some light regarding your inquiries :D

Yes ....!!! They have all flavors...😁😁😁

Yes lots. At least 15-20