For a 10" you would be up for well over a grand for an equatorial mount with tracking, so you can count that out.
You could make your own dob mount, or contact Andrews (
http://www.andrewscom.com.au/) to see if they sell their mounts separately.
Plenty of people have made mounts here, I'd post a question in the DIY section.
http://www.iceinspace.com.au/forum/f...splay.php?f=17
The 1.25" is the barrel size of the eyepiece, they come mostly in 1.25" or 2" sizes.
Your magnification is set by the other measurement (the 40mm),
e.g. the Focal Length of your scope divided by the eyepiece size gives your magnification. I'm guessing your scope has a focal length of 1200mm
In your case the 40mm eyepiece would give you a magnification of 1200/40
= 30x magnification.
If you bought a 17mm and an 11mm you would get 70x and 109x magnification and so on. Not sure what you mean by the image frame.
There is a cheap TMB 6mm planetary eyepiece in the classifieds here, that would give you 200x magnification and a great view of Jupiter on a night of good seeing.
Spectrometers, I'd chat to Merlin66 on these forums, he is into rainbows
With that 40mm eyepiece, after Jupiter, take a look at some of the larger nebulae.