I do have a tip on rolling bombs, actually. You want to turn the Wiimote so that the infrared sensor faces the ground, let it rest by your side, and then pull it back behind you, as if you were getting ready to lob a bowling ball down the alley. If you've ever played the bowling game in Wii Sports, it's a lot like that.
To throw a bomb, just hold the remote up, position yourself so the blue arrow faces where you want to throw, and then flick your wrist forward.
As far as recalibration... that I haven't perfected. With aimed weapons I usually have to do this every time I draw them, but my sword never really seems to need recalibration unless I calibrated it incorrectly in the first place. Make sure you're putting it on a flat surface and not touching the control stick on boot-up, I suppose?