It is impossible to fly in the Reserves/Guard 1 weekend a month, 2 weeks a year. That oft quoted participation requirement is the bare minimum participation in nearly every other field besides aircrew. As an aircrew member, expect anywhere from 5-10 days a month minimum participation. For more info, go to baseops.net and wantscheck.com.
Many people will say you are protected by the USERRA law when it comes to civilian employment, but quite honestly, you could have a tough time with your (non aviation) employer with all of the demands of being a military pilot. You will disappear for 2 years, and when you get back to your home unit, you will probably be expected to stay on active duty orders anywhere from 4 months to 2 years (In addition to the 2 years you were at OTS/Pilot Training) to gain experience (and upgrade to the left seat) until you are cut loose to go back to your employer, if they remember who you are. Understand that while in other career fields, you can be a part-time military member, as a Guard/Reserve Pilot with a civilian job you will essentially have 2 full time jobs.