as you've found through your research....THEORETICALLY (i've never tested this but research and my knowledge of networking supports the concept) you won't be able to simultaneously use the wireless and crossover connection at the same time.....functional wired connections ALWAYS take precedence over a wired connection.....example: i've got a large scale wired network here at work....i've also got a wireless router a few feet from my desk (for visitors)...i can turn on my wireless connection right now and connect to that router....but all my traffic will be going through the wired connection (except for the traffic needed to keep the wireless connection active)...windows is designed to "prefer" wired connections as they're more reliable
i havent researched your bridge so i don't know if it can be used as an ethernet hub/switch...or how many ports it's got on it...but if you had a small (5 ports or so) hub/switch in the room with your sound equipment...then you could connect the switch back to the router...then those machines in that room to the switch...then you'd only be running one cable out into the area with the router instead of 3 or 4....