Getting help in programming while holding the reins tightly

I am starting an Internet business. Basically the most important part, the part that is making me actual money is still missing. I tried to deal with those issues several times but I always get distracted by other things. This is a typical example of not rising to a challenge. I thought about hiring a programmer to continue my coding but I came up with two problems:

1. When revealing my current code the programmer could just run the business on his own. How do I choose someone who won't do that?
2. Which way of payment is appropriate for the programmer in this situation? Per hour? How do I figure out the right amount?

The code to be written will be in PHP + MySQL.

I am in the same boat with you, similar concerns, spent some time researching the topic and found many answers fitting into two categories:

1. "Nobody will steal your idea, people are too busy with theirs, have other stuff etc."
2. Opposite advice - be careful talking to corporations, I talked openly to them, they thanked me and few months later I saw them doing exactly that.

There is third type of advice, less frequent but no less compelling:

1. Learn coding and try it yourself.

I understand that you are already following 3.

To problem 1:

If showing your code indeed reveals the whole concept that someone can take and easily turn into business, then you need someone you can trust. That is, if you are looking for a partner.

But nothing prevents you from approaching things flexibly.
Abstract your code and give your programmer a general piece of functionality, not specific to your business. That way you will get a better code and your idea will be protected.

To problem 2:

If I understand right, you are programming yourself, then it is also the question how much specific piece of code would be worth to you. How much would it take you to write it yourself? What would be the value you could create spending this time otherwise?

Then how good is your programmer and how much is the contribution?
To quote Joel Spolsky, bad programmers and 10 less efficient than good ones.
This is why I am against paying per hour, unless it is a routine work like moving chairs, and even there I'd be worried as it would mean paying more for moving the same number of chairs slower. I would only pay for the work done.

How to figure the right amount? The best answer I've seen is the fairness principle. What both sides feel is the most fair is the right amount.

How to make sure your feelings are aligned? Try with a small project and discuss the reward after completion. If you come to agreement, pay, and continue. If not, hire someone else.

Good luck!