The answer to your first question is yes. The Windows 7 TRIM function and the ssd's "garbage collection" work together. The TRIM function is a message from Windows to the ssd identifying data blocks that are no longer needed.
The answer to your second question is yes. BIOS should be set to AHCI mode for the Intel 320 series ssd's.
Here is a link to a series of ssd guides you might find helpful:http://thessdreview.com/category/ssd-guides/