I have read a lot about indoor humidity level. Some say it should be between 30~40%, others say 40~55%. I also understand it depends on the outside weather temp. For instance, if outside is 0 degrees, one should try to keep the indoor humidity level 30% at most. It is 10 degrees outside, then 35%, 20 degrees 40% and so on so forth.

I have a whole house humidifier (by honeywell) that looks like this
Honeywell Whole House Humidifier

it is fan based, will kick on automatically when furnace supply duct starts supply heat into the house. It is mounted on the supply line and works pretty well.

I recently got a Hygrometer which can tell the humidity level besides the temp. I noticed my 2nd floor's humidity level is at 47 ~ 50% while the main floor is at 38~40%. The furnace and the whole house humidifer is in the basement. The humidity level there is 35% and almost the same as the main floor. Is this normal? I set the humidity level at 30% on the unit but the house seems to be a bit more humid than the set temp (perhaps this may be due to cooking, people and etc.,)

My questions are

1. Is it normal to have the second floor to be more humid than the first? Also the 2nd floor seems a degree or two colder than the main floor (if temp is set at 70 degrees, 2nd floor would be 68~69ish. while humidity level is 7% higher.)

2. I live in New Jersey (south) what is the desire indoor humidity level during the winter when temp is around 20 to 30 degrees?

thanks!