1) No, there is no driver that can fake those flags, it is hard coded into the device's controller.
2) Yes, removing the drive letter (or taking the device offline) will certainly ensure that there are no writes cached for the device, but that is a cumbersome process.
If your flash drive was created after 2012, there is a high likelihood that it is a Windows 8 certified flash drive, which (according to this) means that it is listed as a "Fixed disk" in disk management, and that write caching is disabled by default.
Windows 8 certified flash drives are designed to allow removal at ANY time without damage to the drive's contents. this was designed to support Windows-to-go's "resiliency and unintended removal feature":
The resiliency and unintended removal feature of Windows To Go
automatically froze my computer screen upon removal of the drive,
giving me 60 seconds to re-insert. If the Windows To Go drive is
reinserted into the same port it was removed from, Windows will resume
at the point where the drive was removed – without the loss of in
process work or data. If the USB drive is not reinserted, or is
reinserted into a different port, the host computer will turn off
after 60 seconds.
Even more information is available in this Technet FAQ and this Microsoft blog post.
If your flash drive is listed as a fixed drive - you can verify from the process below that "Write Caching" is disabled by default and safely remove your drive, even in windows 7.
If your drive is listed as removable, do the following to make sure that it is setup to be removed at any time.
Set your device to be "optimized for quick removal" - this will ensure that it is ALWAYS safe to remove.
Plug your USB drive into your PC, then open Device Manager. (Note: These steps are based on Windows 7. Things might look different in previous versions of Windows.)
Expand Disk Drives, then find the entry for your removable drive. On my system, for example, it's called "USB2.0 Flash Disk USB Device."
Right-click that entry, then click Properties.
Click the Policies tab; you should see something like this:
5 . If the first option, Quick removal, is already selected, you're good to go. As noted in its description, "you can disconnect the device safely without using the Safely Remove Hardware notification icon." If Better performance is selected, switch to Quick removal and click OK.
So, what are giving up by disabling write caching? According to the test results posted at 7tutorials, almost nothing. The performance impact was negligible. Your mileage may vary, of course, but I think it's worth a few milliseconds to avoid the hassles of having to mess with Safely Remove Hardware all the time.
NOTE: SanDisk is beginning production of flash drives configured as fixed disk in 2012 to meet new requirements for Windows 8 Certification.
Windows 8 Certification requires flash drive manufacturers to configure flash drives as fixed disks. Flash drives configured as fixed disk will show up in Windows Explorer as 'Hard Disk Drives'.
Historically, flash drives have been configured as removable disks and Windows Explorer displays them as ‘Removable Media’. Windows 8 Certification requires flash drive manufacturers to configure flash drives as fixed disks. Flash drives configured as fixed disk will show up in Windows Explorer as ‘Hard Disk Drives’. Flash drives configured as fixed disks still function the same as those configured as removable disks.