Wow! Lots going on in this query - let's unpack a few:
1) Ries intimates in his book that ideas are plentiful, it's the execution that is difficult, and that's why he suggests to relax about people stealing them.
2) If you hire an outside agency, you'll enter into an IP agreement which either has you owning or sharing the rights to the solutions that are developed. You can/should specify the ideas as being proprietary in these agreements. Consult a lawyer.
3) To test an MVP, you don't necessarily need to create a working app - you could validate the assumptions you're making using other mediums. I've seen MVPs for solutions/services that were first enacted using people, cell phones, clip boards and paper. You want to validate the IDEA to see if it has a customer.
4) Consider learning how to code yourself. Since you'll be building an MVP, you just need to learn enough to demonstrate the core idea(s) and get them in front of customers and maybe even investors or crowd-funders.
5) Consider attending Lean Startup Machine, Hackathon and Lean Coffee events and user groups in your area to meet and network with potential candidates to help you build your MVP and maybe even join your nascent team.
6) Start using the words "yes, and..." more and "yes, but.." less when thinking about what you can do. It helps to unlock latent ideas and strategies.