Virtuemart Expert Wanted

Seeking someone with virtuemart expertise to fine tune and clear our virtuemart site for take off. The virtuemart is installed. Payment currency is integrated. Principally we need someone that can oversee the final tweaks, like ensuring that files ftp'd are done to the correct download directory. Also to ensure that the files for download are located in a folder which cannot be predicted and hacked to over-ride payment. To ensure that there are no security exploits that web criminals can use for phishing and other malicious activity such as the type one gets with Oscommerce. Knowledge of a way for each purchase to generate a unique and random time limited url download link would be an advantage but not necessary. Any other good practice Virtuemart recommendations will be helpful and to confirm that the store is ready to go live.