Did you go back to your old ways completely? Eating bad food, overeating, not counting calories, etc.

didn't eat as bad as before, but still shoved my face full of carbs/chocolate at times. Started at roughly 250lb, dropped down to 199 after 3 months.(Goal weight was 185) And thought "hmm, i can probably just take a break for a few months and eat what i want again". Didn't quite work.. bounced back up to 215-220 and decided "fuck this, I need to be serious".

Did you solely just ingest more carbs, but still remained within the right range for calories and making good choices otherwise?

Not really, I went from being an absolute pig pre-keto, to eating two meals a day with snacks in-between, but the meals were all 'ready-meals' and the snacks were chocolate/crisps

How long did you fall off and how much did you gain?

Probably for four months or so, put back on 20lb, but it plateau'd at that point. (gradually worked its way up over the period of a month and then just halted there). So I never hit my 'maximum' again, but I still went a hell of a lot higher than i liked.

Was the weight gain really fast? Or slowly within a period of time and you noticed, but just didn't care right away?

answered above.

The reason I ask, is because, I am loving keto, but once I reach my goal weight, I don't want to be as strict as I am now (tracking calories, carbs, macros). I do plan on KCKO and maintain a healthy eating lifestyle and still eat within my caloric goal. I just hope with all that, I don't slowly creep weight back on.

theoretically this should be fine, but your mileage may vary. You will still get carb cravings if you eat them every so often and the weight will slowly go back on when this happens. It's all a matter of balance. If you have enough willpower you should be fine. Just remember, if you do break down and go on to eating a shit ton of carbs and putting the weight back on, nothing is stopping you from ketoing again in the future, just don't wait a long time before doing it.