How are people exposing and developing BW negs for scanning?
The only thing I'd worry about is exposing the negative properly. Don't expose it for scanning, just expose it correctly for what it is - a negative.
Different scanning equipment behave differently and as technology improves, a negative that your current scanner may difficulty with will be replaced with one that scans it easily and cost half the price.
My advice on the scanner is buy the best scanner you can afford, calibrate it with an investment in an IT8 transparency target (this is another thread) and a custom ICC profile, learn how to use PS, and you're all set. Oh and buy a large external hard drive - you're going to need it.
Now if you want contrast, you can always add or subtract contrast in PS. There are some plug-ins that also do this better than the inherent PS software itself. I don't use them, but I've been told.
Regards, Art.