Hi,
The software I used with my Toucam is 'Craterlet'...
http://www.stark-labs.com/craterlet.html
This software was easy to use and it is definitely the gain adjustment that is the best to change. The other thing is to set all the automatic settings to manual and slightly adjust until you get what you want.
Exposure settings seem to change in steps rather that linear so set this first to approx what you want.
Brightness I leave as default but you can always experiment
A barlow will always make the image darker than without one, so more gain with a barlow.
There is other free software out there but I have not used with the Toucam. Firecapture is one I've heard about.
The moon is good to experiment on with the Toucam to have a play with settings perhaps.
Cheers,
Damien.