Yeah the F5 is massive, even more so than my buddy's F4s. In terms of walking around with it....I don't....I use my FM2 (oldest/most trusted/beatable body), or newly (year old) bought F100 (praise AF) for that since it honestly isn't worth the hassle/awkwardness/weight. I mostly use it if I am shooting something that needs fast AF and/or need to shoot lots of film quick (sports type things). In which case I have my camera bag (Kata 3-in-1) and strap.
If you are just starting out, even though an F6 might be WONDERFUL, it think alot of its features may be lost on you, considering my FM2 and it's full manual set-up taught me things for years. And if you already have devoted some time and money into the Canon platform, it's probably not worth trying to spread yourself over both platforms (or more) since neither one has something the other doesnt. Most reasons for someone choosing one over the other is either availability, just happened, given something to start with from one, and maybe in some extremely experienced cases...VERY subtle control differences in bodies and lens choices.
As far as developing film.....as a photo student I am lucky enough to have full access to a community darkroom to both print and process film....but unless you have a roll you really cherish and would die for I dont see what is wrong with either going to the cheapest or most convenient place. Since with you negatives you can always re-print an image somewhere else. Just keep in mind, that in most places the kids developing your film won't know/care about photo and only know the steps they were taught and not care if they are green....but as long as your negatives are fine all should be well.
Hope that was at least somewhat helpful! Any other questions? Just ask away!