Re: Frames with crystalized honey...
1. Assuming the hive is healthy, no.
2. True, Kinda. You don't need to uncap it, if it's where the bees will use it they will clean it up. Uncapping may encourage this, but an uncapped box of honey on the bottom may also encourage robbing. If it's badly crystalized and there's a lot of it the bees may not convert all the crystals I have seen them thrown out of the hive like sugar, after being licked clean.
3. Mostly no. But crystalised honeycombs can also ferment because the osmotic pressure of the honey has been reduced. Bees in winter who cannot leave the hive for extended periods, and have to eat fermented honey, can get dysentry.
A general rule if you have these combs would be put them in a healthy hive with enough bees to be capable of tackling the cleanup job and don't overdo it, should be fine. Put the comb in a place in the hive where they'll need to clear it.
"Thinking Inside The Box"