Neither are working currently. (as they should be, anyhow .. they might be doing one thing or another in the current code, but they're not considered implemented)
Yes you will need to deploy the deployable weapons, I am not sure if it will specifically place you in a fire delay, but the deploying process was intended to take as long as the fire delay. Again, subject to change.
Explosives are not worked out yet. I imagine they will be disposed of when used but we shall see!
With my experience with the CVI rotating cannon, the weapon didn't show up until I deployed it. Once deployed I was set into a 30 minute timer, but I tried attacking anyways and it let me, so I had two timers counting down. Also you will need to go through another 30 minute timer to reverse the deployment process when you want to leave.
My bad. I was thinking that since the damage of heavies isn't really finalized/adjusted for their proper role, they aren't implemented. Guess they can be deployed anyway. :>
I was using a Merr-Sonn Mk II when I dropped in to visit Syn, and it didn't require deploying to shoot. Not sure what the go is with that, I'll try with my G-40 when I get it.