sudden temperature fluctuations don't help much, especially down to freezing, here our outdoor weather gradually gets cold, and when i lived in the valley, we got overnight lows down to freezing and below, with no ill effects, but the sudden temperature drop from indoors to freezing might harm them. it will most likely cause them to stop growing and stunt the size of a new growth. cymbidiums are rather hardy though. here we get so much sun that they can sunburn, so can cactus for that matter, so i usually provide the brightest light possible just shy of full sun, at least after 11am. i've never had to bring them inside in 20+ years of living in southern california. they can take summer heat, and winter cold. they do need a drop in temp (and i suspect day length change as well) to initiate spikes, for standards (large) and minis that are not the 'warm growing' types, which are even smaller. they have done a lot of new things with them the last few years, using new species to produce new sizes and colors and shapes. as with any orchid, look to root size to determine size of bark mix used. most need the larger pieces of bark. typical 'large orchid bark mix' works fine. i was told years ago, they like deep pots, and never use a pot that is so big the rim is 3" away from the bulbs. that should give you 2 years of growth or more before having to repot. try to only repot after finished blooming (by then new growth should already be starting) but if the bark turns mushy and soggy, repot anyway, any time.