Your other questions;

Probe position? Transverese and 90 degrees to vein, keep vessel centered on 
your monitor and you can assume vein will be directly under the mid of 
your transducer. Check vessel patency by conpressing and using color flow 
in the sagital view if neccessary.

Position? Knee slightly bent, externally rotated, reverse Trendelenburg. 
Sometimes having the patient stand will help fill the superfical veins.

Who? Whom ever the surgeon has faith in. Perhaps you should consider 
getting your RVT, given you level of interest.  

Please call me directly if I can help (802-656-8827).

Terry Case
University of Vermont