Autostop is not a problem as one of the signals I modify tells the car it is not available so it never tries to do it.
The dc-dc is always on but does stop above 4K rpm due to excess voltage. That's always been an issue with a dead/disabled ima batteries. Note i did propose a partial solution to that on IC but have not had time to build anything to test it yet.
Preventing dc-dc shutdown above 4000rpm or 200v - Insight Central: Honda Insight Forum
Yes you can remove everything, ima battery, mcm, bcm.
You need the connector for the 12V side if you are removing the IMA battery/switchboard.
I'm happy to knock up a couple of circuits if people want them, but the price built is $199 + postage $15 + paypal 5%. It would then just need splicing into the wires in the back.