-You may find phone numbers posted for Harbormaster's office, shore boat service etc. but don't bother. No one picks up the phone, it's all done over VHF radio.
-The Harbormaster's boats will assign you a mooring. If you loiter around at the entrance to Avalon or Two Harbors and hail the Harbormaster via VHF, they will approach, take your documentation information and your cash or credit card payment.
-During the peak summer season, Avalon has a garbage boat that comes by in the morning.
-Not sure if this is the area rbrasi was referring to, but, yeah, watch out for the stuff in the center of the picture, just East of the green buoy, and SW of Bird Rock.
-Also, while there is a lot of diving all over the island, Two Harbors in particular seems to have a lot of dive activity so be wary of dive boats.