Create WHMCS Signup form using API (Fully Documentated)

We need a fairly simple order form created sending the data to WHMCS (Via API) The form both creates the user account and orders the product (only one product). The fields required - First Name - Last Name - Email Address - Password (Hidden) (should randomly generate a strong password) - Country (would prefer hidden and collected via GEOip or something) Then a radio box indicating if they want to use own domain name or one of our subdomains. And then the applicable option which would be there own domain or for the subdomain option<yournamebox>.<selectsubdomains> then a check box which is required before order acceptance terms of service pp etc. I'm not entirely sure of dependencies whmcs needs to accept registration and order in one go but i have seen it before id imagine its fairly simple. This service is free so the default billing option should be selected but hidden. Applicable errors should be displayed in the same page and only if completed successfully they should be redirected to a page of choice. Optionally I'd love to have some sort of simple robot testing thing like word verification incorporated but i find the the google one to clunky and ugly so something neat would be nice. I have a limited budget as this is a free service provided to our customers - If you have any further questions please do not hesitate to contact me. WHMCS API documentation can be found at [login to view URL]