From what I have read,
1. It grows slower then java moss, which is pretty slow since javamoss grows fairly slow. I know in my tanks though it grows fairly quickly compared to others.
2. It's pretty much like javamoss, it depends how fast it grows, and how much light it gets. Some of my stuff takes close to a month, others take a week or so, depending on placement and the way you tie it down.
3. It is pretty much maintance free after it roots down. See with javamoss, you keep having to re-tie or just cut the strands that grow straight up. Fissidens fontanus grows with where it roots, so it will grow along the rock or dw and not just up. You might have to trim every once in awhile to keep it nice, dense, and short depending how you want it to look like.