Be sure that all founders and employees sign a non-disclosure and invention-assignment agreements (and, if allowed in your state, you may want to consider a non-compete agreement) prior to having them to any work. Once more, see your lawyer.
Getting this done UP FRONT is EXTREMELY important. If you don’t get invention-assignment agreements, there’s a danger that your company doesn’t own what’s being designed, and that can lead to very difficult problems (see your lawyer!). If non-compete agreements are allowed in your state, they may need to be executed before the employee even shows up for their first day. So again – talk to an attorney!
Both employee and contractor contracts are something you’ll want to be serious about right at the beginning! It’s worth the lawyer’s fees.