If u perform the extra speed one can u also give it the extra yaw from madine, even if u used madine for the first movement?

No. You can't resolve a navigate command as part of an engine techs maneuver as you had to do a nav to trigger ET in the first place.

And no, you can't bank part of the ability - it has to be spent all at once or it is wasted.

Yeah, you can only resolve each command once per turn. In order to use Engine Techs, you have to resolve a navigate command (even if you choose not to get a benefit from the command.)

So by the time ET rolls around, you've already resolved a Nav command, so even if you still had a dial or token, or hadn't used the effect at first, you still wouldn't be able to resolve that command a second time.