Can an employer change insurance companies in the middle of the year and give the employees less than 2 weeks notice?

Employers usually change their insurance on their renewal date which is anytime of the year. Yours may just have happened to be in the middle of the year. They do not have to give you notice, but even less than two weeks, that's still plenty of time for them to give you information regarding the new plan, what it covers, what your contribution, if any, is going to be. They shouldn't cancel your prior coverage until they get approval from the new company.

Yes