Re #4: The relationship between the two sentences in the small snippet isn't entirely clear to me, either, but it still makes sense given the system in the US. My understanding is that they are saying that if you are going to get online classes from a university that is much more expensive, you might as well meet your general education requirements at a community college instead and save money (which doesn't preclude the possibility that the classes could be held on-line there as well).
Re #5 & #7: also fast schon an die Volkshochschule Ummm, no. A community college in the US has many functions, including serving as a trade school and offering certificates of study, but also offering university-level instruction (and often even an Associate's degree). The university-level instruction at a community college is what is being discussed here. This has been possible for decades in the US--you do run the risk that the university may not accept all of your credits from the community college on a 1:1 basis so that you may have to take an additional course or two. (My university, a large, well-respected state university, had a close relationship with the local community college so that it basically accepted all coursework done there.) Depending on your field of study, these "general education" classes can easily take up much of your first two years at a college or university before you get into the more specialized classes in your field.