How to use cast-iron teacup? I love my cast-iron teapots; however, for Christmas, I received a set of teacups to match my latest acquisition. Do I pre-warm them like I do the pot? Or is the intent for it to leech some heat out when poured so it's drinkable faster? They appear to be traditional Chinese-style: small and without handles. They also appear to be enameled on the inside, to match the pot. 

Also, is there anything I should know about the care and keeping of them above and beyond the usual cast-iron advice (no soap, dry well, et cetera)?
I've never found cast-iron teacups to be practical to actually use.  Not only do you not want to warm them before pouring the tea in, after you pour it in the cups will be to hot to drink out of.  One has to wait for the tea to cool to lukewarm before it's safe to touch one's lips to the cup.

As far as cleaning them goes, you can use soap and hand-wash, just don't put them in the dishwasher.