In my planned setup I have two machines: a connected machine (HOT) and a non-connected machine (COLD). My plan, in the event that I need to send bitcoins, is that I will:

1. formulate desired transaction in JSON on HOT as [TRANS]
2. copy [TRANS] to COLD
3. sign [TRANS] on COLD turning it into [SIGNED]
4. copy [SIGNED] to HOT
5. transmit/execute [SIGNED] on HOT to complete the transaction

My questions are:

A. How can I determine what the earliest/latest versions of bitcoind will work on both COLD and HOT? For example, I am currently running 120100 on HOT. Is that good enough? How can I know for sure which versions will work and which will not at any given instant in time in the future?

B. Do I need to have the blockchain on COLD? My understanding is that I do not.

C. There are two forms of JSON transactions, simple and raw, the raw being the more complete. Does [TRANS] need to be raw or can it be simple? I assume [SIGNED] must be raw, is that right?