I agree with you about the length allowed for disputes. Usually there is a technical reason for a dispute, and it is nearly imossible to put the needed amount of information into the limited space allowed.
On the subjecot of sources, if you go to the details screen and click on each event - birth, death, etc., if nFS has any sources for that event, they are listed. This helps to narrow down which "sources" go with which events. Although the majority of sources now included were put there at the creation of nFS and tell where each item originated in Old FamilySearch, you will also find sources which were included by submitters in their Pedigree Resource Files. (Relatively few in number, however.) Remember the PRF was the only database that allowed the inclusion of sources in submissions. Most members of the church don't appreciate the importance of sources.
In my experiment to see how nFS handles uploading of sources, I uploaded a group of 100 names which included vital record sources and combined them. The note at the end of the upload indicated that they were all new names - they weren't - they needed to be combined. Then I added some additional sources to those names in my PAF file, such as census records, social security death index, and World War 1 Draft Registrations. I ulploaded the same names again with the additional sources, plus some new names. My experiment was to see if what I had read about GUIDS (called Unique Records Serial Numbers in PAF) really worked. In this second upload, I did not have to combine the entries I had previously uploaded - they were combined automatically, however, the message I received at the end of my GEDCOM upload indicated that only 8 individuals were not new. A second problem that occurred was that the vital record sources were not recognized as duplicates and were listed a second time. For example, see Everett Alvin Lewis, b. 1888 PID KFD4-NCQ
I am anxious to be able to have access to the images of sources, but I don't anticipate that will happen for many years. Many of my sources are vital records obtained from state or county sources, and if I want them to appear, I will have to scan and upload them myself. I wish these genealogical sites that we pay money to would focus on scanning and indexing old vital records rather than obtaining images of old newspapers, 99% of which have nothing to do with genealogy.