Is Amazon's shoe size chart true to fit with this particular pair of Timbs?

YES！The length of my foot is 27.5cm, i chose 10.5, alought the shoe size is a littler bit large, but it prove the size chart is true. i think 10 is perfect fit to my foot's size.

Are the soles glued down inside the boot/shoe?

The soles are glued and stitched in. You can also can easily take the cushion out and add another in it. It's a nicely crafted shoe that is water resistant and comfortable. I wore them in the snow and they kept my feet dry and warm. They also have good tread to prevent a lot of slidding.

Anyone use these as workboots?

Have been wearing them for years, have to replace about once per year in my framing days, they last a little longer now. After 6 months or so and they are starting to wear, you can walk through water but I would stand in it to long. Will leak overtime, they are not rubber boots!