Leica Weitzler

I found an old Leica Weitzler binocular scope at an auction that takes
place tomorrow. Its very dusty but appears serviceable. I couldnt find
a model number or name other than Weitzlar, and didnt get the serial no
but I'm guessing its 1950's-early 60's vintage, being black not brass.
It seems to have been a quality scope, with a rather large, swivelling
binocular head, geared stage movements, 10xWA eyepieces and 10, 45
(iirc) and 100 X objectives. I want something cheap for examining
fungal spores and related structures, and I cant find any info on these
on the web. If anyone knows anything about these,

--I dont expect this will go for more than $10-20 if that (I'll be
surprised if anyone bids but me), but can I do a lot better for that
money?

It doesnt have an integral light source, but has some sort of
horizontal tube about 2' diameter that runs up to the mirror. Do I need
a special light to use this? Does this make it a royal PIA such that I
shouldnt even bother?

I want oil immersion capability, do all 100 x lenses have this abaility
or do you need a special oil lens? The 100 doesnt say anything about
oil on it.

lastly, I do have a 100x oil lens (Spencer) from roughly the same era
on an old monocular B&L. If necessary, is there any hope that this lens
will thread in to the Leica scope?

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