There is a trolley tour but if you have a car you can drive around and stop at all of the scenic lookouts and park and hike too. You can bring or rent bikes and bike the carriage trails as well.

Bar Harbor doesn't really have any sand beaches for swimming. Other than the swimming pools at the different hotels and motels in Bar Harbor, the closest beach that I saw was Sand Beach, which is about 4 miles south of Bar Harbor, just off of Park Loop Road. We were there in the 3rd week of August and the water was still pretty chilly and there weren't many people swimming.

Yes, with a leash of course.

Yes, both. There's plenty of room and it's fairly level... enjoy

It's about 1/2 mile in each direction.

Yes

There is 2 hr free parallel parking all over downtown Bar Harbor. There is also several town parking lots all off Main St. or Mt Desert street, the trouble is that the town is usually packed from mid day to late afternoon and then the dinner crowd. If you have patience, you will usually find a spot without too much effort. If you can walk 5 blocks or so from the center or town and shops, you will find more spaces. Cottage street usually is good for us to find parking. The shore path can be accessed from about 4 different streets in downtown, depending upon how long you want to walk and which direction. There is a public parking lot right by the path on I believe Albert Meadow, and also down by the town pier. Just obtain one of the many info maps before you get on the island. There are info buildings on the causeway and one downtown on the corner of Cottage street with all the menus, maps, and go to places that you would want.

The shore path is free. It is not part of the national park system so it does not require a park pass. Just walk whenever you want.

Your option for the ferry to Nova Scotia is to board in South Portland, ME. I believe it is now called Nova Star Cruises.