These are all some great questions. For your first question, you can change the map movement speed of the player party in general by using the "Move Event" command. If you only want it to apply when a certain actor is leading the party, you could probably set up a parallel process Common Event that checks whether that actor is leading the party (you would need a script snippet to make that check, but it should be easy KK20 would know what it is,) and sets the movement rate accordingly.
As for your second two questions, those are actually both really useful features that unfortunately aren't included in the default RMXP experience, but either of them should be pretty simple to add with a bit of scripting. I wouldn't be surprised if there aren't scripts out there already that help with that kind of thing.
I hope that helps!