Yes, you can resoftmod your Wii, just follow the Softmod ANY Wii guide linked in my signature (though if you're having troubles with memory loss and such due to your recovering from stroke/brain surgery I recommend against doing ANYTHING with Wii modding. If you mess up your Wii that is no ones fault but yours)
Calibrating the WiiMote without a game depends. Is it a Motion plus controller or a standard Wii remote? You can try de-syncing it and re-syncing it and see if that helps.
To check your NAND space simply go to Wii settings, data, save data. It will tell you how many blocks are left.
Again, if you mess up your Wii it is not our fault. For this reason I recommend you have someone else (who knows what they're doing) do it for you or wait until you have recovered.