I'm wondering if you are able to return to certain areas once your finsih with it? I'm just wondering if I miss a weapon or blueprint if I can just go grab it?

I here there are vendors in each area. Can I always reach them.

Example: I missed the wingstick, can go grab it or have a chance to grab the blueprint somewhere else. Is it easy to miss these things or is it pretty direct. Thanks

There are no blueprints just lying around you either buy them or complete quests for them. That being said you can back track as much as you want. You can always go back to Loosum and learn how to make wingsticks