If I load my bitcoin loaded wallet.dat file into the newly installed Bitcoin-qt, because you say the encryption is in my wallet.dat file, will the option to encrypt be greyed-out? (I'm not experimenting or doing anything until I fully understand).
It'll look the same as it did before:
(I don't really understand the question, why would you think it would be different when it's the same wallet?)I thought the idea of the encryption is to password protect the wallet.dat file? If the encryption is in the bitcoin loaded wallet.dat file, then if someone else gets hold of my file, the encryption protection would be meaningless?
I
still don't understand your reasoning. Whoever gets hold of your wallet.dat, needs the password before he can use it.
When the bitcoin loaded wallet.dat is loaded into the newly installed bitcoin-qt, will I be able to transact straight away, ie, move bitcoins to my exchange, or do I at some stage enter the encryption password?
It works exactly the same as it does now: you make a transaction, and enter the password before sending.
I was keen on preparing a paper wallet but frightened off as I'm reading that if loaded using the private key, and then spending a part of the total, my wallet becomes empty.
That's why you should always spend the entire balance from a paper wallet at once. You can easily do that by sending it entirely to your own wallet (this is called swiping, very easy if you use a mobile wallet and QR-code), or you can send the change to another paper wallet (this is a bit more advanced, as you need to manually set the change address). You can even use the same paper wallet again, but that's less private and less secure (I do this sometimes though).
Think of any paper wallet as a very big dollar bill: you can take it out of your wallet, but you can't rip it in half and use only a part. You have to use the whole bill, and you have to safely store the change you receive afterwards.
The big warning to use the whole balance comes from this scenario: someone has a 100BTC paper wallet, uses his hot wallet to send 1BTC from the paper wallet to his friend, and then assumes the remaining 99BTC is still in the paper wallet. He removes his hot wallet, and it turns out his paper wallet is empty. His 99BTC was in the hot wallet now.My advice:
try it. Take a small amount, put it on a paper wallet, take it out, get a feel for it.
I think the easiest thing to do now is just make multiple copies of my wallet.dat file, on usb sticks and CD's. I read that USB's and any flash card may not be reliable long term. I would have thought CD copies will be reliable long term.
CDs age, flash drives age, hard drives can break down too. An easy solution is to make new backups on a regular basis, just like you should do with all your important data. And test your backups once in a while, to be sure they work and you know how to restore them.