Do you not have the option for Spanish 4? If you do, I’d recommend that over starting a second language.
You don’t need another AP in the mix so take what interests you most. I’ve heard the AP art courses are very time intensive.
Difficulty and time is so variable school to school that you are better off asking an upperclassman you know what there experiences were (or the teachers of guidance counselors).
FWIW, my D felt that Calc was just a natural progression from pre-calc. Not a big jump in difficulty or workload. AP chem was one of the toughest classes she took in HS (after AP Physics C). She had a first year teacher though so there was a lot of self teaching going on so very time intensive. APUSH and AP Lang had a lot of writing but in her school those two classes complemented each other.