Unfortunately no, Metro rail won't be running to Reston until late this year at the earliest. There are Metro buses available, but as you'll see from the bus map (a .pdf available here: http://www.wmata.com/pdfs/bus/VA.pdf?) it is a spaghetti collection of routes that can be hard to decipher.
Your best bet is to go to the Metro route planner (upper left hand corner of www.wmata.com, click "advanced" to be able to enter street addresses), put in where you'll start and where you'll want to go, and follow the directions provided on which buses to take at which times.
To get to Baltimore, your best bet will be to get yourself in to Union Station in D.C. (reachable from Reston by a combination of Metro bus to Metro rail), and then taking either MARC rail (a commuter railway) or Amtrak to Baltimore. It'll be a long day of connections, but can be done if you map out your routes and departure times in advance.