Also if you were to continually connect and disconnect the BNC connectors, in your guys experience, do they wear down and if so how quickly?
I would not connect/disconnect the BNCs all the time. While this will be no problem in the short run, connectors have a maximum number of "mating cycles" for which they are guaranteed to work. It may be less than one expects, see the datasheet (USB would have a quite large number, DVI on the other hand, well...). What I could find for BNC is 500 mating cycles, which is, hmm, less than I would have expected =8^(.
At one extreme, when I worked at ESA, we were allowed just one cycle of SMA connectors on flight hardware! I used to think that this was actually self defeating, because if you need to replace both connectors each time you've cycled them, the effect on the rest of the system is worse, such as thermal cycling of the PCB, although cable ends were always crimped, but of they were loomed up, you might end up having to re-loom.
Practically it is a lot more than that: I have a test jig for one of my products, and it takes around 6,000 cycles before the jig's male connector starts to faulter. The failure mode is always the centre pin, it is visibly thinner after 6,000 cycles because of the abrasive effect of the female receptacle. After a while, it no longer makes reliable contact.