A "walking" vehicle

I would like to understand which are the minimal parameters and functions to call to create a very simple vehicle that moves as a "walking" person. Slow, mostly on the ground. Not a real vehicle too but an object that moves while you use controls and the "sit" avatr is animated how if he would walk. Should always a vehicle be physical? I would prefer not to be physical. Is it possible?

If you use the vehicle functions (http://www.lslwiki.net/lslwiki/wakka.php?wakka=vehicles) it must be physical. However, in the more general sense of the word "vehicle"--being an object that moves under a resident's control while the resident's avatar sits on it--you can certainly make one that is non-physical and uses non-physical movement functions.

The movement functions you'll use for a non-physical object are llSetPos(), llSetRot(), possibly llLookAt() or llRotLookAt() for a rotational alternative, and possibly llSetPrimitiveParams() to set both position and rotation at once (for a single script delay rather than two).

You'll also want to capture the user's controls with llTakeControls(), and you'll want to animate the avatar with llStartAnimation() and llStopAnimation() (to do each of those you'll have to obtain the PERMISSION_TAKE_CONTROLS and PERMISSION_TRIGGER_ANIMATION permissions respectively using llRequestPermissions(); if a single script is doing both, obtain both permissions at the same time). For built-in animations you can use see http://www.lslwiki.net/lslwiki/wakka.php?wakka=animation but you can also use custom animations.

Actually I just re-read your post, and what you want to make, is an "anti griefing vehicle"...

I have an open source one, made by Jesrad Seraph, I'll send it to you inworld. There's also one that works a little nicer (not open source) in the freebie Mysti-Tool. You can pick one of those up, and sort of get an idea how the freebie one can be improved with additional functions.