Regarding scanning modules/software, if you truly want to have control over every aspect of your scanning, and if you want to be able to scan directly into 64-bit Photoshop (TWAIN only works with 32-bit applications, not 64-bit), I recommend VueScan:
http://www.hamrick.com/$29.95 for a license with 1 year of upgrades, or $79.95 for lifetime upgrades. You can download and run it as a trial before purchasing.
I use it both from within Photoshop and as a standalone scanning application. It allows far more fine-tuning than any WIA to TWAIN driver.