Some Q's

I recently got a promotion and have to travel 52 miles one way instead of 28. My two current vehicles are a ML320 which gets about 18.2mpg and Ram Hemi that gets 13.6mpg. I was looking for a awd car with good gas mileage. I have come across a 2005 Subaru Impreza 2.5RS at a local dealer.

First question:
Is $17k a good or average deal for a 05 2.5RS with 27k on it?

Second Question:
Is there anything I can do to increase the mpg. For example put a larger exhaust on it and a cold air intake to allow the engine to breath better?

Thank you in advance for your help.