I had a problem with my router and it picked up the closest ip it could (being 192.168.0.2), shouldn't happen again, and, do I use the internal in putty or the public...
I haven't seen my IP change since i've gotten my connection...so yeah, but, how do you mean append the, ":17222" to it?
If you are at home, and you want to SSH into your FreeNAS, you need to use the internal address, because you are on your internal network.
If you are away, it would be impossible for you to even see your internal network ip addresses, unless you are tunneled into your network in some fashion (via SSH tunnel, or VPN), so obviously you would use your external address to connect to SSH from remote.
When using PuTTy, you will notice it has a box for a port number. if you decide you want to use 17222 as your external access port, then you would put THAT in the port box in PuTTy. When internal you would use port 22.
When I mentioned forwarding a different port number, I meant exactly that. Leave the FreeNAS port alone, no need to change it, because it is default at 22.
In your router, you would forward port 17222, to port 22 on the FreeNAS IP.
If you leave your work laptop on 24/7, and you have the ability, you might attempt to run an OpenVPN server from it (it uses UDP port 1194) and you would then have a VPN into your home to do whatever you like on your internal network.
Pay attention to the rules of setting up any VPN. Do not use the same IP subnet for the VPN as you use for your internal network (ie, if your internal network is 192.168.0.2/24, then use anything BUT that subnet. I prefer 172.16.0.0/24 or similar to keep them separated). Beyond that, it will be a matter of getting your router to recognize that new subnet, but that should be fairly easy.
Based on your router model, I am guessing you have a pretty basic DSL connection? You might want to check your upload speeds with that, because you will not have much fun trying to transfer/use files remotely on a slow DSL link, no matter how you configure your way into the network.