Hi, Brian.
If I mapquested you correctly, you are in that wonderful land surrounded by Lakes Erie, Ontario, Michigan, and Simco. Beautiful country.
What are your goals for the pond? Which species do you want to maximize the growth of? Or are you interested in a more balanced, diverse population?
Do you know what species of sunfish you have? BG are very prolific and produce a great deal of forage for predators. If you don't have any BG, you
might consider introducing them.
3) I feel I should be stocking some minnows and I could catch these from a local creek, but i am concerned about introducing another species and possible disease that they could bring.
Those are valid concerns.
Feeding predators by restocking minnows is an expensive (if you buy minnows) or labor intensive (if you trap and transfer) proposition. IF you are able & willing to feed regularly, this would support many of your species directly (certainly BG & trout, most probably YP, quite possibly SMB; even LMB are capable of learning to eat pellets when hungry, motivated, and shown the way by other fish eating them regularly), and would indirectly help non-pellet eating predators via increased forge fish reproduction & growth.
Our Northern-tier PMs should have a good idea what you can do with your current (and possible additional) forage species.