First issue:
the “Reserve” and “On” lines exiting the bottom of the tank (see photo) won’t go in the IMS tank. Are those plastic tips necessary?

Are the plastic tips necessary. These lines will not fit all the way in the IMS tank. They bottom out before the threads reach the imbedded nuts in the under side of the tank.

Second issue:
no way I can get the rubber grommet off (where the rear of the tank meets the front of the seat) without breaking it or cutting the metal ear on the old tank.
Third issue:
The instructions… “the stock tank has two hoses connected to the bottom of the tank, the California models have three; none are used with the IMS tank”… what? There only are the two gas supply lines on the bottom of my tank. They go to the petcock.
Fourth issue:
The instructions: “to get a proper seal, the stock o-ring on the small threaded brass fitting (it has the standpipe) must be replaced with the 2x8mm o-ring provided”.
”standpipe”? Threaded brass fitting? The only threaded brass fittings are the supply lines that exit the bottom of the tank, neither will accept the supplied o-ring.
Fifth issue:
What's a "separator"?

You really need to contact ims tech dept and ask those questions. Really don’t you think so ?

I had put a little (very little) thought into making a locking cap out of something. A quick fill flange (this isn’t the one ims sells) would need to be done, which would involve cutting the plastic neck out of a ims klx tank. And that’s where my thinking came to a halt