I think your concerns regarding how DD plans on working through this are best addressed by them. When I was there last weekend, they were in the process of rearranging the shop and effectively blocking off everything past the entrance way. I think the plan is for "us" to drop our tanks in that little vestibule area where a staff member will disinfect them, fill them, return them, disinfect them...
Or at least that's what they were discussing last weekend. This is hard for all businesses, and dive shops are facing challenging times. Honestly, I'm grateful that they're open at all. I suspect Mike and Kelly had that discussion... Take the year off.
As far as I can see, paid parking is not in effect (yet?).
I think if you are expecting an easy solution, you're best to pass on coming at all this year, or leave it until later in the season. Or perhaps bring enough tanks to get you through the weekend.
As for the rest of town, things are slowly coming to life. Take-out at the Crowsnest (with lineup), and Princess. Hotels are looking like they're ready to open, ATM is open, grocery store, LCBO etc. Masks are appreciated.
Bear in mind that there is still a travel ban in effect in Ontario and the border isn't open. I could count the number of tourists I've seen on four hands. The ferry starts Monday, but only for essential commercial traffic. It's slated to open to everyone late June I believe.
Remember that diving makes up a tiny proportion of the tourism spend in Tobermory. It's impossible to know what the summer will bring. Some businesses may not open at all if the non-diving people don't return.
I rent my place out on AirBnB. We can't operate at all at this point, although I am almost fully booked for July and part of August at this point, which is behind last year, but looking promising.
When you are packing your gear to come, I recommend packing a double load of patience as well.