Some yeast strains produce more diacetyl than others. In my experience, it's never a bad idea to do a diacetyl rest even it if may not be strictly needed. It can't hurt, might help is my philosphy.
If you need more yeast at bottling, you can add it. I don't save the yeast from primary, I just add 1/3 package of dry yeast to the priming solution.
Broken Leg Brewery
Giving beer a leg to stand on since 2006