The 1.8L has a timing chain. Don't hear of too many problems with the timing chain, but I have heard of a lot of head gasket failures on the 1.8L.
As far as your audio system, you should have a door speaker in each of the front doors, a tweeter in each of the front pillars, and three speakers under the rear parcel shelf, the center one being the subwoofer. Refer to speaker "D" on the diagram below. I would highly recommend Crutchfield.com for replacement audio componants. Fair prices and great service!