Have a look at
http://www.lumicon.com/telescope-acc...ensity+Filters for some information.
Also
http://www.bintel.com.au/Filters.html which are available locally.
The ND96 (13%) transmission filter is all you will need in either 1.25" or 2" depending on which eyepiece you will use it with most. The 25% filter is fine for crescent phases of the Moon.
My experience with polarizing filters is that that they have a detrimental effect on resolution (small craters simply vanish!).
Colour filters are for highlighting planetary details of various colours. eg. a red feature will appear darker with a blue filter.