4. To prevent taxi and runway incursions the flight crew could have the HUD display hooked up to a ground based moving map display and when the aircraft requests start and pushback ATC, would download the taxi route and runway destination into the moving map and the pilots will follow this via their HUD’s. When the aircraft gets to an intersection, hold etc… a voice would tell them to turn left/right/stop/caution/you are at the destination runway.
Not all airports will possess the capabilities. Maybe a screen with a map of the taxiways of the aerodrome that it is currently at where you can select the taxiway you are cleared to use, shows your current position and all the moving aircraft in the vicinity. Not sure how plausible that is but it sounds more "do-able" than that HUD stuff.