Barry,
well done for your early efforts! it get both more rewarding and challenging as you progress.
In response to your stacking question you may wish to consider deepskystacker, free, i use it all the time.
http://deepskystacker.free.fr/english/index.html
noise can be removed by many different pieces of softare, you may wish t start with noiseware community edition, free,
http://www.imagenomic.com/download.aspx
(it's the last link at the bottom of the page)
cheers and have fun!
frank