Given temps in your area and the riding conditions I'd consider moving the jet needle's clip to the second from the top position (#2), install a 152 main and fine tune from there.
I'd stick with the #7 plug and jet with that.
"Bike lacks power like when new is this normal" Yes poor jetting zaps a pile of power and throttle response.
When to service the top end? That's not an easy question to answer, there isn't a one size fits all answer and it will vary greatly depending on how you ride the bike, maintain the air filter etc. I'm do a compression test now and record the value in your log book then periodically take compression reading, record them, and compare them to the original.
David