Yes, with stopped down metering, you meter at the shooting aperture and try to get the meter needle to line up with the index mark in the finder. I find wide open metering to be more accurate in general. At low light levels, in-camera meters can become non-linear, and when you use stopped down metering, you're reducing the amount of light striking the photocell, so you create a lower light level condition, and you might find that the stopped down reading and the wide open reading don't agree.

Unless there is some particular FL lens that you really want, there are still plenty of pretty cheap FD lenses, both with the older breech-lock system and the later bayonet system (sometimes referred to as FDn), so I'd go for the improved functionality of the FD lenses. Some people prefer the sturdy feel of the older chrome mount ring, and others prefer the updated optics and coatings of the later bayonet mount lenses. Most of mine are the later versions.