[Swarm-Support] Walk to a spot on a 2d grid? 'Sense' the presence of another agent in the vicinity?

[Jurgen van der Pol]

Ok, I'm going to ask a lot of dumb questions now and then for a while, 
probably asking for beaten tracks, sorry.

Context for those interested: I'm putting swarm to use in the supply 
chain management/logistics domain. Making a model (using 
simpleObserverbug2 as a starter template) in which I want a  number of 
agents to live: trucks, cargo, depots. Trucks to go to a depot to pick 
up cargo and deliver it at a given destination.

How do I

- tell an agent to 'walk' to a certain spot on a 2d grid? Is there a 
method available? If not, any coding suggestions (quickest path from A 
to B)? Like [truck walkToX: xDestination Y: yDestination]?

- have an agent 'sense' the presence of another agent fulfilling 
certain conditions? Is there a method that looks/scans around for 
something (i.e. if an empty truck happens to get near a depot, and 
cargo is present there, it should 'sense' this and go pick it up)? Like 
[truck getNearestAgentWith: conditionA andWith: conditionB]?

(Starlogo, which I used once in this regard, had methods for these 
things)

Thanks again, more beginners Q's to follow I'm afraid...

Cheers,
Jurgen.