Can i use a glue gun to glue my tracks to felt on my layout.
Well, you could, but it would be very messy. Hot glue wouldn't harm your felt or your track, but it leaves a very shiny aftermath which isn't good for scenery application if you choose to do so. Also, it is stringy and would tend to land in places where you wouldn't want it to. If you want your layout to be permanent, use track nails.