specification of "Lens filter diameter" or "filter diameter" will have screw-mount threads for doing what you want. If the spec is not listed or marked "N/A", then assume no threads. Generally, the low end of the spectrum will be "N/A". What is your budget?

Which camcorders have you looked at? It appears that all the Canon HF series at canon.com have the Filter Diameter specification and a link to lens add-ons. The low-end of the Sony and Panasonic camcorders do not have the Lens filter diameter listed - but the mid-range and above, do;

As for "decent low light", I've noticed that DV (onto Digital8 and miniDV) handles low light better than the new non-tape camcorders (especially high definition) - but the same rule applies - large lens and large imaging chip make for better low light performance. Once we know your budget, we can see what fits and set the lighting behavior expectation.