What are the first 4-6 miles of the Minong like?
Uphill?
Is it scenic and worth it? Will we likely see many people?
I'd need to go back to my notes to see where you drop off the final ridge (which has some amazing mature white pine trees, as I recall) as that might be within 4-6mi. Much of that section is in the woods, though; and not the most scenic the trail has to offer. I've spent years attempting to suppress the memories that are the long, up/down/up/down/repeat slog that is the hike from North Desor.
I would doubt you see many, if any, people.
Does Hugginin get crowded at all? We would be there 3 nights total and are looking for a more quiet area to stay.
"Crowded" is not a common Isle Royale term. I'm not sure I've ever seen that camp full, which actually surprises me given the distance from Windigo. With maybe exception to Daisy Farm and Rock Harbor during peak season, I think most camps are pretty darn quiet.
What are the bugs like currently, and/or late June? Are they better or worse on the north side of the island?
There will be bugs. Black flies might be on the down-swing. Mosquitos will probably be around, especially on the trails and valleys. Campgrounds on the "big lake" can have highly variable bug conditions, mostly based as a function of the wind direction. If you get a breeze off the lake, you might not see any.