400 for a timing belt & oil change? Why so much? Never heard you have to change the oil right when you change the timing belt. Although I usually recommend changing out the "water pump" whenever you get your timing belt done.

The car should not shake whatsoever, if it didn't beforehand after a timing belt replacement if it was done right...which sounds to me it wasn't. I would suggest taking it to another mechanic (if you're not mechanically incline) to have them check to see if the belt was replaced appropriately..that they set it to TDC correctly and check timing with a timing gun. I wouldn't take it back to them until I find out what kind of damage they may have done and have them pay for it.

And no, your spark plugs should not be broken from having a timing belt replaced..unless some serious detonation may have caused it...which would not be a problem if they had did everything correctly.