Lots of good stuff man. Looking forward to seeing more of your armor paint up.
For the boots, you don't need specific fabric paint, but just regular acrylics. I did this indoors, and it dried in no time. It's true that the canvas does soak up the paint - which is good actually. I would recommend an acrylic wash for the boots over rattlecan any day. The wash spreads the paint along the canvas, giving it an airbrushed look. From your pics, I get the feeling some areas on your boots are a bit blotchy. What do you think? I think you can fix that with some sand paper and water to blend the harder lines. Don't be afraid with acrylics. You can always paint over top