Bench grinder wheels. Recommendations

You have a disc or a stone, sanding discs are nice for some things but I use a 100 grit stone for grinding lathe bits it's not as good as a green wheel but it works.
100 grit is great for grinding more precision stuff I would keep that and go with a 8" wire wheel. As far as stone dresser I have used a diamond dresser but found that a stone works the best, and they are cheap and last forever. This is the one I have been using for the last 5 years and it still looks like new.

McMaster-Carr