Yes, it has a set of plastic dividers that you can add as needed, if you are only doing 6 eggs I would put them in the middle because the corners get cold.
If it is small enough to put glue on the back and stick it to the inside of the incubator, it should work. Just be sure to do a test and make sure it reads the right number.
If you are looking for a cheap incubator, I would not pay less than $55, and this incubator is on Amazon.com for $65, but it is still very cheap compared to other incubators. It has given me two hatches, one I got 10 of 15, and the other I got 6 of 12. This time I am going to hatch Japanese...