Narrower tyres are good for commuters but dont to too far. You need something fairly tough and reliable.
I find that a generous 28mm size (Schwalbe Marathon ) is about right for year round use although I could use a thinner one in summer. Money spend on a kevlar protection band is well spent.

You could lose a lot of weight by replacing the sus seatpost, adjustable stem and sus forks. Good ridgid forks can be quite springy but cheap ones are too stiff for comfort.
Do you have a track pump and is your bike kitted out with decent luggage, lights, lock etc.