You still lose the weight, but you retain water during TOTM so the scales do not always reflect the loss.
I used to gain weight at TOTM which did kind of mess things up in my head - best to look at average weightloss over time than just that particular week. If you lose 4 lbs one week and 0 lbs the next - that's still 2 lbs per week.
No, it depends on YOUR body , everyone is different, I have lost weight in the past and still lose now during totm if I am dieting...just keep well hydrated and the water retention should be held at bay (most of the weight is water weight after all totm)
Yeah it does vary from person to person, you'll just have to keep an eye on what seems to happen to you personally around your TOTM - and if you keep a food diary, check if it is TOTM water retention or if you end up eating more around then from cravings.
It seems to be a fairly common footnote here and there when people report a gain though, when I do get TOTM (keep having big gaps in mine, not had one since middle of October) it didn't seem to make much difference. But I do drink loads, like minimum 3 litres of water a day so it probably helps