sounds like a good mechanic to me.
starters can spin slow like your describing when the motor starts grounding out. if left the starter will eventually fail and if it takes long enough for the starter to completely fail you can damage the ring gear as well which is very costly.
Stay on good terms and keep him around, your being looked after properly. All the parts you list I replace frequently.

If he was bad an alternator would have been thrown in the mix too. this tells me he actually diagnosed your problems.