Planning a Visit in June - Couple of Questions

Hi! I'm planning my first Pacific Northwest trip in mid-June (flexible through mid-July) and am planning to stay a couple of nights on the San Juan Islands. I'm going to link up with a friend in Seattle and then we'll do a couple of days in the islands and a couple of days on the coast/parks.

Ideally, the more adventurous part of the trip will be the coast and national parks, so we're looking for a mix of relaxing, enjoying the scenery/nature, easy to moderate activities, and eating some delicious food.

My primary goals for this trip are to relax and to enjoy the beautiful landscapes and nature in the Pacific NW. I'm from DC, so that's pretty non-existent here :).

I have a couple of questions for the "pros" out there:

1) For planning purposes, is it easier to get to the islands from Seattle or from the coast (Rialto Beach or Olympic Park area)? We're still working out logistics, so we're flexible as to what leg of the trip the islands land on. Also, if anyone has any recs for national/state parks/lakes or the coast that are somewhat "close," feel free to let me know.

2) A friend recommended staying on either San Juan Island or Orcas Island. Is one better than the other? How easy is it to ferry around between the islands? We'll have a car, but we don't necessarily need it to traverse between the islands, correct? I'm also open to other islands.

3) How difficult is it to get ferry reservations from the mainland to the islands?

4) Is 3-4 days enough?

5) Any recommendations for lodging? Where should we look to book if we want scenic views?

6) Food recommendations?

7) Any must-do activities or places to visit while there?

8) How far out should be book everything?

9) How much should I realistically be prepared to spend?

Thanks so much in advance!