Again on 172SP 2003 Bandix/King GPS unit. On this plane there is no separate DME stack so I have to use DME on GPS it self. For example, I know that I need to plug in LAX instead of KLAX and reference distance from LAX to shoot the approach, get MAP or/and stepdown fix since it's VOR distance that's referenced rather than airport.

Having said, I have two questions.

-When I dial in VOR Identifier on GPS to use as DME, it takes rather longer time than planes with DME stack it self. What I mean is on Bandix/King, I have to click "direct" then use two knobs to set the alphabets and click enter twice in order to activate. However on older DME unit, you just tune the frequency and it's activated. I know it's only couple seconds of difference but I think couple second in IMC is pretty significant. So my questions is, are there easier or quicker way to dial in VOR station on this model GPS that I'm missing out?

So to clearify, this is what I do. EXample, Click "direct" dial in "LAX", click "Enter" "Enter".

-When I plug in the airport rather than VOR, which part of airport is GPS measuring to? Is it center of runway?Airport?

Thanks!