1) I can't seem to get a consistent %change figure for a month on month comparison from GA. Looking at simple metrics like monthly users and sessions.
2) Is it possible to have a single table with a month on month, and year on comparison? So looking at this months users and sessions, and how they compared to last month and this month in 2017. I only seem to be able to do this by having 2 tables and duplicating all of the current month data in both versions.
comparison is a bit tricky. Best tip for it is to use full months / weeks, for example if you are using "Month&Year" as dimension, choose the date range so that it it doesn't include this month as it's not complete.
Best way to avoid comparison results not to show, is to not use any date related dimensions in the Split By.