Hi there, great to hear you're coming to Scotland this summer! I'll try to respond to each of your questions in turn.
In terms of booking, since you're coming in peak season I would probably make a booking in the more popular locations, including Skye and anywhere on the NW coast. Elsewhere, if you arrive by mid/late afternoon you should be fine. A good compromise might be to book in advance at the sites you know you'll definitely want to stay at but then to keep other arrangements reasonably flexible, and then just call ahead that day when you'll know where you're likely to be when. I've listed my top 10 recommended sites here
Informal camping in a campervan or motorhome is tolerated in Scotland but we don't have the same space as in Canada and so potential sites are perhaps more limited. In tourist hotspots (see above) possible informal camping spots can get congested which has led to growing tensions. If you want to camp informally within the Loch Lomond & the Trossachs National Park you'll need to apply for a permit in advance (see here
) - but note there are also campsites in the NP where you don't need a permit. Common sense and 'leave no trace' principles apply! Take a look at my blog post on the subject here
In Edinburgh my recommendation would be Mortonhall
, with easy access into the city centre by bus so you don't need to pay for city centre parking. Glasgow's a bit more difficult since there aren't any sites in the city itself. I'd suggest camping at one of the Loch Lomond sites and then taking the train into Glasgow from Balloch - perhaps Cashel, Milarrochy Bay or Lomond Woods. That way, you'd combine a peaceful scenic site with the hustle and bustle of the city.