Question and I will preface this by saying I have not had time to read the entire thread so I am sorry if this was answered.
Does 2019 save files different than 2018? For example if I have someone make a scene for me and they are using 2019 will I be able to open it in my 2018 version? Thanks
Yes they do load in 2018 but you'll get some plugin errors depending on what they've done. Reasonable to expect that.