"I'm okay with it if he truly does bring in work and isn't just dicking around all day"
I think if that is the attitude you're taking going into this, partnering is a bad idea. You will constantly be judging & nit picking his every action.
You started a business in the same industry as freelancer.com, leveraged off their service and have an almost identical name; how did you think they would respond?
In hmexx's scenario, once the MVP is ready, the developer has received the full amount of cash which is likely the main incentive.
In your proposition, the main incentive is your coding ability.
The key difference is that in the first scenario, the cash is a measurable benefit. In your scenario, your coding ability is uncertain, it could be worth more or less than the cash you are requesting - it's hardly worth gambling 50% equity on ones self-proclaimed ability.
This proposition provides far less value than hmexx's.
I understand what you're saying about "execution" being more important than the idea - that is true, but execution also means follow through. Building an MVP and then ditching it to pursue "the next project" is not execution, that's just pure labor, which anyone can find for far cheaper on elance.
I prefer this to the standard cover letter, but make sure you don't come across too arrogant. e.g. this line is unnecessary in my opinion: "Do you remember your first CS class? How there were a few people who just couldn’t handle the obscure bugs and the hours upon hours of staring at the screen and they ended up dropping out?".
I will be signing up and if the videos are as good as the samples I'll definitely be sticking around; worth $49 a month for sure. I love that you guys are trying to tackle this end-to-end - ambitious, but I hope you pull it off.
Side note: I am currently looking for a co-founder CTO to help with continuous improvements/iterations, so if anyone is interested, please get in touch via email (in the profile).