3-5% is still actually healthy for a male. However it isn't advisable to go that low if you're looking to just stay healthy, ripped and fit. Those percentiles are usually found for marathon/endurance runners.
8-12% for you should be absolutely fine. Its a multi purpose/ideal body fat range for most goals.

I'll let someone else comment on Nutrition as that varies from person to person.

IMO it sounds like there isn't any need for you to cycle tbh if your goal is just to maintain muscle and stay healthy. All I'd suggest is probably just a simple bump up on your test and maybe throw some anavar if you wanna diet down without losing any muscle.