That's not a great amount of oil loss, given 110K miles. Sounds like a typical amount for an engine with that amount of miles, plus maybe worn valve stem seals, so I would investigate that end of it. I would find out how long the previous owner had it and if he either had valve stem seals done, or a head gasket replaced. I would be a little concerned about traces of oil in the coolant, but if the previous owner had a head gasket blow out and then fixed it, I wouldn't be as concerned. There is a coolant overflow tank in the right fender that often doesn't get changed when it's contaminated by a head gasket failure. If it doesn't get replaced, it can cause continued coolant contamination after the gasket is fixed. Actually, many times the pressure tank isn't even replaced, although it should be, as cleaning it doesn't work very well, and it isn't extremely expensive, I usually recommend replacing both the pressure tank and the overflow container if the coolant has oil in it.
As I said before, the usual sign of valve stem seal wear is a "false cold start" complaint, deposits on the spark plugs, and also a slight oil consumption problem such as this.
I would say you are good to run the synthetic oil out to about 6 to 7000 miles between changes no problem.
Don't be too surprised if the mechanic recommends the belt tightener for the fan belt, this is quite common when doing the waterpump.