Research Project - using proxies to access site(repost)

Research Project to explore proxying options available to PHP5 bot. I need a primer on the practical aspects of using a proxy service. Including operational problems that might be expected with free proxies (e.g. keeping proxy list uptodate) as well as the advantages (and disadvantages) of paid proxies. Recommendations (and otherwise= on paid proxy services would also be useful. We have a bot that performs regression tests on a web app. This bot should now be able to use multiple proxies to emulate multiple users from different geographic regions. I require a written report explaining the options available. Should examine, free proxies, pay proxy services. Do anonymizers like TOR offer anything useful? Is it possible to know (or select) in advance which IP will be seen by the service for a particular test case? I expect you to have done projects like this before and to be able to provide real world solutions and practical tips. Happy bidding ## Deliverables Written report. Should include simple PHP code samples for proxy configuration. Nothing too complex. ## Platform PHP5 / *nix