I've got a Cobra handheld that I hooked up to the Autocom and I've used it occasionally. The handheld sits upright in a pocket of my tank bag, so the antenna is pointed straight up. This has proven to be the best location for it. If the weather get's ugly, the only option is to stow it in the tankbag and hope it doesn't get too wet, as it is NOT waterproof by any stretch of the imagination.
Every radio you hook up to the Autocom seems to have it's own unique cable, and trying to figure out which one you need can be a bit of a puzzle. Ideally you'll have an Autocom dealer close by who can help you decipher it all.
Once hooked up, the reception I got was mediocre... lots of noise and interference, even with the squelch cranked up. You HAVE to run the CB on it's own power or your noise issues will be even worse. Raising/lowering the windscreen will fill your head with the most God-awful squealing you've ever heard. There are apparently noise chokes that you can add that will help. Despite all that, the CB is ok for monitoring the trucker channels and NOAA weather, and the dope you can get on traffic and LEO activity up the road can be very helpful. If the noise really gets to you there's always the on/off switch...
I've all but given up on using CB for transmitting... the range with a rubber duck antenna is abysmal, and I've had a lot of difficulty hearing or being heard. I don't blame that on the Autocom, it's one of the limitations of a handheld CB radio. If you intend to transmit (and it sounds like you do), you should consider hooking up to a good quality 3 or 4 foot no-ground-plane antenna, and then get someone with an SWR meter to dial it all in properly. This should improve both clarity and range by a considerable margin.
I may do the external antenna at some point, but at present I've pretty much relegated the CB to monitoring only and use a FRS/GMRS for the rare times when I want/need bike-to-bike comms. The Goldwing folks do seem to use CB a lot, and most seem to like it, so maybe it's just me....
Hope this helps.
Griff