Question 1: that's what I did. Might want to search for older discussions on wiring up a diode between the socket and fuse holder to blow the fuse if power is ever hooked up wrong.
Personal note: It would have been easier to put in the VK3YE DDS noise filter if I planned it in first.
Question 2: I tried rotating mine in the first time. Made the mistake of pulling on the pot shaft and broke it, so I had to take it back out.
Question 3: My case came with 12 screws of the same type. M3 with a flat head with a rise in the center where a Phillips/Cross-head screwdriver goes. I used 4 to mount the Bitx40 board to the case without the standoffs. I stacked the Raduino together with all 8 standoffs, 2 in each corner. Nuts behind the Raduino. After everything else was installed on the front panel I was able to mount the Raduino through the clear bezel using some of the longer M3 case screws. (Might want to take the protective plastic off the LCD before to limit reflections and blurriness later)
Question 4: There was a few discussions on what should be the standard for wiring up one of the mic TRS. Tip=Mic, Ring=PTT, and Sleeve=Ground. Or Tip=PTT, Ring=Mic, and Sleeve=Ground. Black wires from the Bitx40 headers are ground for my description.
I found some of the electret PC mics I had on hand would work as is with mic, PTT, GND so I standardized on that.
All in all, I like my Maroon Universal II case. I use a log pot on the upper Mic mount for RF gain. If I didn't love the RF gain so much, I'd have put a momentary button for amunters Function button.
The other hole I want is one to bolt the IRF510 to the back. Still needs an Isolation kit since the tab is PA_PWR voltage+. That would let the final amp use the case as a heatsink. One of these days I'll take it to a drill press and add 3 holes.
73 de Jacob AG7CT