your worry is pointless; the benefits from CC'ing units pretty much outweigh everything else. the only few units you might ever consider not cc'ing are phyllis and assal who might be better off pre-CC for UP generation (note that they are not meant to tank anything)
edit: you can ignore the event until the last 4 days. until then, refer to https://www.youtube.com/channel/UCbI...tD5TDCRrOW1kXg
use the video guides to clear up till castle retake, then move on to desert story missions if possible (again, youtube for videos)
you'll eventually want the following at 50cc30 100% affection asap: bashira, katie, soma/daniela, iris, alissa, valerie, leeanne, cloris, elaine.
for affection, clear challenge missions (refer to eth eternal video up above) up till phalanx 2 and 1* skip the maps in between if necessary.
edit2: recommended team composition basic: http://harem-battle.club/millennium-...-1-2015-a.html