Combined stats are the stats on your profile. NOT the numbers in the red and blue bars. That is your energy.
Intelligence + strength = combined stats
Cs (combined stats) is anything from 0-999
Kcs (thousand combined stats) is anything from 1,000 - 999,999
Mcs (million combined stats) is anything from 1,000,000 - 999,999,999. Stats dont go up that high yet but you get the point.
Misc stats are a combination of stat items, pet, relationship, dorm room ect. Theres a full run down when you scroll down on your profile.
Misc stats help make you strong to help defend and attack in pvp. So they are only really important if you are involved with pvp.
If anything its better to have no stat items if you arnt involved with pvp coz a farmer legally cant take ec value items for cf. So furniture, premium drops, name change, rs break ect.