VATSIM / couple of queries

sorry i cant help you on all questions but the 3nm from location you can check your gps and you can see the waypoints/jetways on that i believe.

Frequently when taking off in VATSIM my IAS (just left of the artificial horizon indicator in the 737-400 default panel) seems to show as 0 - I think this is related to the weather d/l from squawkbox but it makes it difficult to use my IAS hold switch so some help would be appreciated on that point.

Your pitot tube freezes, turn pitot heat on.

In flight when I level off (using autopilot) I find my planes nose is constantly bobbing up and down like a ship on a rough sea - what causes this?

Some "bobbing" is normal (winds aloft cause that usually) but it shouldn't be noticeable or annoying. Which model are you using? What kind of weather? Do you use time compression? (you shouldn't).

I am aware that when tuned to UNICOM you are supposed to regularly readback your position which is ok but how do I know what my position is.

You are not supposed to update your position all the time, just when something important is changing (taxi, take off, TOC, TOD, intention to cross a transition point, altitude changes, approach, final). Other than that... how do you navigate? You should know what your position is, either using a VOR/DME and chart or GPS/RNAV (FMC).

I know where I'm coming from and I know where I'm going to I know what flight level I'm at but I dont know that I'm (for example) 3 nm from the Honeley VOR.

Just tune the Honeley VOR. You will get a distance measurement from your DME equipment ;P