I think he is trying to do changes in the upcoming chapter by doing minimal changes now to give content or he wants to take a small break for him self by doing minimal changes to art and delivering some thing to read on time
Remember Me chapter 14 has been absolutely great so far. I think the gradually worsening punishments and humiliations Julie endures are very appropriate and engaging.
Nope, Use 7Zip (or plenty of other Archive-Applications) on a computer, and they are fine to open.
Edit:
Even it weren't to be open as an archive, there is still the tool HJSplit...
00x files just mean, that you need a tool that is capable of merging the parts together. HJSplit is able to merge OR to cut a file/archive into parts.