From your description and looking at the video, your sheet mulch looks great.
Looks like you did everything "the right way".
In short... just be patient, it's should work great.
1) Should I just be more patient and give it more time to compost
- yes be patient, it will continue to break down
- go ahead and plant in it this year, maybe use a couple handfuls of compost if you're starting seeds
- continue to mulch over the top throughout the summer
- by fall/winter it should be looking great, and by next spring it should be dark rich soil
2) If there should be more progress in composting at this point, if I've done it properly?
- I don't see anything more you could have done
3) If I can dig holes thru the layers of sheetmulch, adding compost to plant seedlings into it for now?
- for new sheet mulch, I generally just use a spade to scrape a small hole in the mulch, add some compost and plant my seedlings
4) If the composted manure may have contained wood shavings in the bedding that I didn't account for and if it's going to take a couple of years to break down, perhaps?
- the manure looked fine... yes there was some shavings, it will break down
5) If adding something like Bio-tone® Starter Plus 4-3-3 (Endo & Ecto Mycorrhizae) would help get things moving along once I get some plants in there or other some ideas?
- don't bother adding anything more, you have a great sheet mulch
To give you some perspective.... my sheet mulch bed last year was:
1" - 2" compost
2" - 4" grass hay
4" - 6" leaves
1" - 2" poultry bedding, grass hay + chicken
Those were the ingredients I had on hand, so that's what I used.
It took a bit longer, but it worked great.
This year, the bed is looking spectacular.