1) Memory is non-switched (aka - direct to battery...maybe with a fuse between it, I don't know) power source that provides juice to the head unit so it remembers presets.
2) Most of our cars (mine, at least) has a three antenna system and a computer to decide which antenna, or combination of them, is used. That computer is turned on or off by that lead. Additionally, it turns the stock amp on or off.
3) need to hook up the Amp ON from the head unit to the aforementioned power antenna lead
4) common grounds for the speakers (note how you don't see a negative for each of the speaker leads on the stock head unit, but your aftermarket has them).
best, whit