Δαφνη Ευτυχια Αρθουρος

There is a particular type of relay that I have never heard of and thus do not know the name of. But I want one, and so it must exist, for I do not think that, at the level of relays, my electronics projects and skills are in the 'esoteric' range. (Of course, rule 34 means that there must also be porn about this type of relay, but that's a tangent that almost certainly can go unexplored.)

The relays I'm familiar with are the "normally open" and "normally closed" varieties (where applying power to the coil either opens or closes the switch, and when the coil is not energized the switch is in the opposite state), and various combinations of that (more poles, more throws ... the first relay I ever played with had both an NO output and an NC output, so energizing the coil selected the NO line and de-energizing the coil selected the NC one).

But what I want is a relay where applying power to the coil toggles the state, and the state thus selected persists after the coil is switched off. It doesn't matter whether it's one coil that toggles the state back and forth, or separate "open the switch" and "close the switch" coils. What matters is that the relay latch and stays latched when there's no power flowing to it.

What is that kind of relay called?

Related question: for an automobile battery, what gauge wire is the smallest I should use for hooking up everything except the starter? Do I just add up all the fuses, multiply by twelve, and look for wire rated for that many Watts, or is there a general "this is usually enough" rule I can use to purchase the wire before I get my hands on the vehicle?

I've got a spool of 10-guage, and I'm pondering just running several pieces of it in parallel to add up to whatever I need, because the "battery cable" at Advance Auto os two bucks a foot (but if the length I need is less than I expect, that might wind up not being unreasonable -- I don't know yet).