I am not an expert at this but you might try logging in with your Bitcoin address and then either adding your gpg key or changing it if for some reason it thinks you already have one.

Since you are already registered with your bitcoin address, we will log in with that.

After you enter.

;;bcauth <USERNAME>

and it responds with

<gribble> Request successful for user strello, hostmask <my username>. Your challenge string is: freenode:#bitcoin-otc:cb8fc47fe135ef14878d84f92cc3d6##########

Paste the freenode:#bitcoin-otc:cb8fc47fe135ef14878d84f92cc3d6########## information into the bitcoin client and sign it.

Then take the returned signature and enter it like this. For this authentication you do not need pastebin.

;;bcverify <Signature>

You should receive the following message

<gribble> You are now authenticated for user <USERNAME> with address <Irrelevant information>

Hopefully you can now add or change your gpg key.

You probably have already seen these but these links are extremely helpful.

http://wiki.bitcoin-otc.com/wiki/Bitcoin_address_authentication
http://wiki.bitcoin-otc.com/wiki/GPG_authentication

Let me know if I failed completely at being understandable.

Hope this helps.

While I am certainly not very knowledgeable regarding miners at the moment, regarding your latter questions I recommend you check out some of these calculators. They are very handy for knowing exactly how much you could make, finding the time it will take you to break even, and comparing different mining equipment.

http://bitcoinx.com/profit/
http://tpbitcalc.appspot.com/

I find it quite entertaining crunching the numbers and imagining the crazy and unrealistic amounts of money the calculators say I could make.

Note: I did not create these calculators and I deserve no credit.