I think it does offset some experience, and I definitely believe it will certainly be beneficial for you to obtain it. I'm not sure if any of theses are free or not. If you're proficient with one language, focus on that. Visual Basic is expansive, and very, very few people are experts in all aspects of the product. However, the exams expect you to demonstrate understanding of all aspects of Visual Basic.
Salaries vary across the country.
However, studies show that you earn more with an MCSD than you do without one. I want to get certified soon. I have heard that it has changed to a case study type format with fewer multiple choice questions. The 70-175 format is the same as most other exams. The only case study exam I am familiar with on the MCSD side is the Solutions Architecture exam.