Been on the trail a few times and many times on the JdF just to the south. It is just a little drive down the road from me.
If you can hike in mud and slippery terrain, you will do fine with regular shoes. Hiking poles are a must.
Yes, the times that you are looking at will be busy but there is lots of solitude on the trail. Pick your preferred start date ASAP. Long weekend start times will sell out right away. Southbound will sell out before northbound. Also make reservations on the West Coast Trail bus if you need to get back the start point. If you want to save a few buck and hike a bit longer, Yo-yo the trail and save yourself nearly $100 and several hours on the bus. Pack Gravol for the bus.  The trail is worth hiking both directions. Mention it to them when you do your orientation. You will have to pay twice for the river crossings, but not double the trail fees.
Have you considered reversing the direction of your hike? I think that it is a better hike going north rather than south.
What are your plans for getting to the trailhead? You can catch the Clipper from Seattle (sans car) to Victoria and then catch the bus to the trailhead.
For a few more miles you can tack on the JdF Trail with the WCT. If the tides are in your favor doing the JdF should only add 1 extra night.
Let me know if you have any other questions.
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