I wouldn't bother with the RAW file for black and white. It gives no advantages in film scanning black and white (for color, you can change white balance, which is nice). Here's what I do. Scan using the black and white negative setting in the INPUT TAB.
Here's the settings for each tab:
INPUT:
-Black and white neg.
-16 bit gray (vitally important. don't even consider scanning as 8 bit).
-Preview resolution: auto.
-Scan Resolution: Whatever your scanner's highest is. My Nikon does 4000dpi. Don't scan lower thinking you'll make smaller prints. You'll regret this deeply when you decide to make a larger print and have to rescan and redo ALL your post-processing.
-Auto Focus: Always (if you scanner offers this...flatbeds don't usually)
-If you use a Nikon scanner use FINE MODE. Don't bother with multisampling, it does nothing for BW negs. Use it for slides.
Filter Tab:
None for all filters.
Color Tab:
-Set white point and black point both at 0% to avoid clipping of highlights and shadows
-leave curves and brightness settings at default
-Output colorspace: Gray
-Leave the other settings at default
Output tab:
-Printed size: Scan Size
-Tiff File (not raw or Jpeg!)
-Tiff compression: None
-Tiff File Type: 16 bit Gray
Your scans will be flat. This is NORMAL for neg scans. Add contrast and adjust tonality in LR or photoshop or whatever. You want the flat scan to make sure the whole tone range is captured in the scan without clipping.
Scan without editing...right from scanner
Edited version
Right from scanner
Edited.