1. Your download analytics are only available for yourself, we don't make them publicly available. Are you concerned about your own downloads confusing your analysis when you look at the graph?
2. We do preserve the individual file download counts on deleted files, I don't see an issue with displaying the last X uploads on the Files section of the game analytics page, but it could get cluttered. Alternatively, if you upload a file with the same name, or use butler, then statistics are preserved when you update a file.