Hey there, I'm new here and a beginner for 18 months, so bear with me! I use Two Fuji 69's, Rolleicord 4, and two mamiya 35mm systems. So far!
So here's my first post. Disclaimer: I have never used the camera you refer to, too expensive!
TTL means through the lens, so all the information you get about exposure etc. is coming through the lens and will be what the film sees. You can use filters etc. better that way since the changes are measured TTL.
With most cameras of that ilk you can adjust the aperture or shutter speed to give a correct exposure, according to what the meter is reading. Aperture priority is where you might set an aperture of say 5.6, quite wide, then the meter gives a corresponding shutter speed automatically, thus giving a correct exposure.
2. A rangefinder works by using the image as seen through the viewfinder and the iage from the lens to focus, two separate images. You Twist the focus ring until what you want to see in focus is in focus. The focus patch is in the center of the viewfinder and has a split-image, two images. If you point that patch at an apple and get the two images to co-incide then you will have that apple in focus. The advantage of rangefinder focus is that you can always get maximum light, rather than focusing through the lens as all slr cameras do. So, rangefinders are good for low light stuff. Also, you may want to do a Google search on Hyper-focal distance focusing, it works very well for fast street photography, a la Henri Cartier Bresson.
3. Exposure compensation is what you use when you want to change the exposure setting just slightly, a stop over or under, thus giving a slightly brighter or darker photo. It is useful when metering scenes like snowy mountains etc.
4. You can always use a light meter, the camera has one, I think. Anyhow, most light meters will be fine, try a very sensitive one like Profisix, for low light work. The best light meter you can have is your brain, so you can get used to exposures. Example: I know that if I use my Fuji 69's with Efke 25 film on a bright day, the correct exposure will be F5.6 @ 1/60 sec. or thereabouts. The light meter is designed to prevent you guessing!
Buy it, and don't be paranoid, it is far simpler than learning digital. The analogue world has alot to offer, and prices are low. Try ebay, I saw one going cheap.
All the best mate,