As in any airport, your flight will have a gate assigned. Gate numbers C30 or higher are bus gates. Gate information will be available about 3 hours before the flight.

A380 airplanes hardly ever leave from bus gates (too complicated). B787 airplanes or smaller will typically leave from bus gates, and arrive at remote stands.

Maps of the airport and the gates are available here. All bus gates are at the North node of the airport; Al Safwa is at the South node. It takes about 20 between the two nodes. There is a train between the two nodes.

Gates are clearly marked and signposted. Just follow the signs like for any normal gate. There will be a seating area (shared for all classes) and a boarding desk (with seperate entries for economy and elites).

Busses will wait outside, about 10 m behind the boarding desk. There is a small holding pen between the two.

Staff will advise passengers to wait until a bus for their class (Economy, Business or First Class) arrives. I generally prefer to simply board the first available bus anyway, as I prefer my business seat over waiting.

Staff will often hold other passengers so waiting elite customers can enter the bus first, and grab one of the few available seats.

They can look up the gate number, deduce from that if it's a bus gate or not. I suppose they could try to explain how to get there.

Maybe they can arrange one of those electric carts for you.

Not normally.