The weight of wheels is in a few recent discussions. Comes in around 30 lbs total
I think (tire + wheel).

Honda has decent info about the IMA, the video is good, I went looking for the link, couldn't find it, but it is in this forum somewhere. THere are links to both the 2003 and the 2006 HCH IMA videos, they are on www.hondanews.com I think so you might find them there.

Weight efficiency estimates come in around about 1mpg per 100 lbs, up or down.

Haven't seen much on aftermarket mods here, mostly people drive the cars stock.

There is no glossary, you are sort of on your own there.

For an MT (manual tranny), shutting off the key and putting it back into the II position is called a reboot or a Forced Auto Stop (FAS). The safety considerations are that the brake pressure will drop as you use the brake pedal, and the mechanical backup requires very strong legs to get significant braking, try it and you'll get a feel for it.

The power steering will also cut off briefly, it is electrical so it comes back, but a few seconds after you put the key back in the II (run) position. The mechanical backup for the steering isn't too bad, you can drive the car that way (I can even do it one handed). I have an MT and use FAS a lot, but not at freeway speeds, I tend to use it at low speeds and when the engine is cold (Auto-Stop doesn't come on until the engine is warm).

Enough brake pressure to come to a full stop remains during an FAS, and it is using the brake pedal that loses pressure so you can control it fairly well.

I think most people coast with the engine on at high speeds just because the efficiency gain is slight, and for cases like prolonged downhill grades you might as well charge up the battery as go FAS and risk reduced brake and steering control. That said some of the better hypermilers in this forum routinely reboot down big hills, it does help.