[RBS] Recommendations for co. to bill through?

[The Jerenbergs]

I would be grateful if anyone who is billing for work done, via a company 
(in order to remain a "sachir"), could contact me off-list with their 
recommendation. I need to know if the company you bill through takes a 
percentage or a lump sum or both each month, whether I must charge VAT, how 
easy it is to work through said company, as well as any other details you 
think are pertinent.

TIA,
Batya Jerenberg