There are several moms playgroups in Snohomish on meetup.com. You can also check out yahoo.com --> groups. I did a search and also found this one: http://www.mothersofsouthsnohomish.org/. Meetup.com has the most options for you though, so I definitely suggest checking them out. Most groups are free.
Having a support group of other moms around is so important, especially in the first year of your first child's life. That was the hardest part for me (with the life change) and when I needed other moms the most. Other moms are also the best resources for everything!
For activities, you may want to check out a book called "The Seattle Mama's Handbook", which has TONS of stuff to do with kids and as families in Seattle and the surrounding areas.
If you're in south snohomish county, you might want to check out Woodinville Family Preschool (www.woodinvillefamilypreschool.org). The "preschool" part is misleading, as it's more of a parent education program for the first couple of years (that provides your child a great play environment), that turns into a preschool as your child gets older. (You and your child attend together.) It's a GREAT community of parents, and the parent educators and teachers are so wonderful and amazing to help you through the beginning stages of motherhood.
I wish you the best of luck! :o)