You could use ONE access point on the other side. so you get wired or wireless access from there. Say if you want to put a wired printer, etc
Depth of trench: it depend if you want to do it by building code,if you bury cable directly or in a metal/plastic conduit; under concrete etc.
In a metal conduit, 6 inches should be ok (can be less (4 inches) under concrete) less may be fine if you don't care about code.
While you are at it put a second conduit in case you need it later.
Maybe there is already a conduit you could reuse.
Depth of trench: it depend if you want to do it by building code,if you bury cable directly or in a metal/plastic conduit; under concrete etc.
In a metal conduit, 6 inches should be ok (can be less (4 inches) under concrete) less may be fine if you don't care about code.
While you are at it put a second conduit in case you need it later.
Maybe there is already a conduit you could reuse.