Hi. Perhaps you could look at buyingh the same printer from here at click here or here click here , both cheaper than dell and offering a 2-year on-site warranty.
In answer to your questions
1. Dell should release the official drivers for Windows 7 once it is launched, however I am sure you can use the exisiting drivers under compatibility mode
2. From the dells site : "Use and Return assures environmentally sound recycling of used toner cartridges".
3. If you purchase from one of the links posted above, they offer 2-years onsite warranty as standard. MOre information on Dell ProSupport click here