Schools - It depends. For the most part yeah Fairfax has good schools and some great ones Thomas jefferson, but you have to basically apply to go there. There are also some crappy schools in Fairfax. In Alexandria, everyone I know who lives in city limits sends there kinds to private schools, because they can, and they don't like the schools.
Cost of living, especially housing is expensive. Sales tax, income taxes are cheaper. Property taxes depends on which city/county.
There are areas of Fairfax I won't even go through, makes NE DC look nice.
Yes the commute really sucks. Theer are days where you are lucky to go 5 miles in an hour. Again depends on where you are going and from where.
As far as living, if you like the country area, think south or West. Stafford, Fredericksburg, Spotsylvania, Mannassas, etc.... There is plenty of subways, virginia rail, and other commuter options, but it depends again, where you are going, when and where you are coming from.
If you want, send me a pm with specifics. Company, housing costs expectations, etc...