1) use paper towels, not tissue. make sure the paper towel is wet/damp, but it in a saucer and cover it or put it in a dark warm place. Just check occasionally and make sure the paper towel doesn't dry out. This is just the method I use, there are tons of other opinions out there if you search "germinating"

2) 1/8th of an inch. I've heard arguments for both root up and root down but I believe the best approach is root down. Plant it about a 1/2-1 inch deep. Plenty of info on this site about that (look up stinkys newb guide).

3) You can put the light on right away, although I don't believe it makes a difference until the plants actually have leaves to use the light in photosynthesis.

goodluck.