I'm just north of Glasgow so can probably help with any questions for much of Scotland. If you want to place a high priority on avoiding traffic the Sustrans Routes are always good. Not the most direct route but avoid traffic using either off road routes or very low traffic roads.
EV1 and EV12 are known here as NCN1 and NCN7
https://www.sustrans.org.uk/find-a-r...etwork/route-7
https://cycle.travel/route/summary/156588
Other things to know? If you want to use a train to skip a section - all trains carry bikes without any packing or disassembly other than taking pannier off. Long distances routes need a bike space booked at the same time as your ticket. These are any route from Scotland to England. Glasgow or Edinburgh lines to Inverness, Aberdeen or Fort William. Local services - no booking required. Just turn up. Same for Glasgow - Edinburgh.
Booking can be done at any main station. Or online.
Long distance bus routes carry bikes with a booking.
https://www.citylink.co.uk/condition...iage/bicycles/
Presumably you are camping? If not I would suggest carrying at least emergency camping gear as north of Inverness accommodation is limited and may be booked up in May and June.
Budget hotels. The Travelodge chain has good coverage nationally. I have been able to take my bike into the room any time I've used them.
Usual rules about being careful with bike parking in the big towns and cities. I wouldn't stay overnight anywhere in Glasgow or Edinburgh if my bike was locked outside. Smaller towns you are OK.
Camping? With rare exceptions camping is allowed on any uncultivated land. Usual common sense rules. don't camp near houses etc.
https://www.outdooraccess-scotland.scot/