There are several Plustek users on here, but relatively few Silverfast users. I have a 7500i, and used Silverfast 6 for the first few years, until MacOS changes meant it stopped working, when I switched to Vuescan Pro.
As far as I understand bit depth, you will want to use as much as you can get, particularly if you're saving to (16-bit) TIFF. I don't remember a SF setting for bit depth, but it was many years and versions ago!
The whole DPI thing is confusing. Even at scan time, it sometimes seems to refer to the print stage. As Ian says, 300 dpi is fine for most printers, although I believe some printers work best at lower settings.
To avoid confusion, I prefer to use samples per inch when referring to settings on the scanner. On 135 film, 1200 spi will give you a small file with little flexibility. 2400 spi should give you a file in the region of 8 to 9 Mpixe, 3600 pixels along the long side, that should print up to 8x12" (realistically, you can go larger if you want). 3600 spi will get you 19 Mpixels... However, you should perhaps read filmscanner.info on this scanner at
https://www.filmscanner.info/en/PlustekOpticFilm8200i.html (note, not a full review), which reminds us that the maximum effective resolution of the scanner is 3250 spi (although you might have to scan at 7200 spi and downsize for that).
As far as sharpening is concerned, I do none at the scan stage, and choose how much sharpening I want in PP.
You might be interested in the
Big Film Scanner Thread...
