I don't use minnows or shiners, just jigs. The concession at the main boat ramp on 616 sells minnows. Their number is 804-693-2107. They will be able to tell you what they sell or give you directions to a local bait shop. I can't think of anything along 17 before you get to the bridge. There is a fishing store on 17 in a strip mall across from Grafton Garage (Dodge dealer), but I've never been in there.
It has been a few weeks since I've been there. The weed beds are beginning to turn over and that makes trolling tough.
I've had my best luck over top the weed beds along the main lake channel. As you leave the main boat ramp, go to the left and turn right as you get to the main channel. You will see some stumps and fish attractors along the left of the lake as you head north. Just past where the stumps come a good way out into the water, there is a weed bed to the left of the fish attractor with an Osprey nest on it. Across the lake and a little further north there is another stump field with a weed bed paralleling it. I usually catch 50 - 100 per trip in these areas. Most of them are 9 -9.5 inches in length. I try not to keep anything under 10" unless it is hooked in the gills and is going to die if released.
Let me know when you plan to come this way and how you do.