I run a consulting company. We’ve done work for Square and numerous other companies of all shapes and sizes.

1. Hire a person, company will cost you more since their rates “are blended”. That means you are paying more for a company since they include the cost of a project manager, et al.
2. You have to decide your budget. Do you have 5,000? Do you have 10,000$? It’s whatever you’re willing to spend on your initial build. Budget has nothing to do with how much the project costs, it’s what you’re willing to spend.
3. Same as budget, we’ve no clue what you’re idea is about, so can’t even begin to understand how easy or hard it is. We get the cost and time question every single time, there’s no way to get that information until we’ve heard some details.

Good luck. Obviously, we could schedule a call on here if you want to go over that.