Using a buis like troy, mi, arms, or other low profile flip sight...assuming there's not a continuous top rail (just the railed receiver), what are my options for mounting a conventional scope, and what rings/mount would work? I don't want a large scope, but just looking at it, there doesn't seem to be enough room on the receiver, lengthwise. Not worried about clearance as the appropriate height rings will take care of that.  

Would the best thing be to utilize a QD thumbscrew on the rear buis so i can take it off quick to make room for scope and mount? if so, do most sights accomodate a QD screw or is it model specific?

check out LaRue scope mounts.  love mine.  quick disconnect and retains zero if you take it off and put it back on.

i'll even give ya a link
http://stores.homestead.com/Laruetactical/Detail.bok?no=30

that's pretty sweet. didn't know how to describe it, but that's it...although a  little spendy for me. gonna see what i can find for a little less. anybody know of a reasonable facsimile that's about middle of the road, price-wise? i don't want a pos that won't return to zero, mind you.