- Keep the FT lead source for that opportunity as the original program and not this new one, as the opportunity previously existed
YES.
- Don't count this as a conversion for the program (again, no new opportunity created)
Yes, it WILL count as a conversion for the Program this if your lead matched a Success status in that Program. If you setup your statuses to match your funnel, then I suppose it may not.
- Count a MT touch for this program and that opportunity
Yes, it will count as an MT touch because it has a Contact Role on the Opp before it closed and reached a Success in the Program. Again, if it did not reach Success, it will not count. If your process did not attach the Contact to the Opp fully, then it may not. But check your Admin > RCE settings. If you use Implicit or Hybrid, this will still count for MT.