1. Split it between you guys, and handle investors later. When a new shareholder (investor or employee) comes in, all existing shareholders dilute equally.
2. Yes. 4-year vesting with a 1-year cliff is typical. Sometimes single- or double-trigger acceleration.
3. 60/25/15 seems really unbalanced. Is the product built and launched yet? Do you have users? If you haven't launched yet, I'd do 33/33/33 or close to it, since most of the work is ahead of you. If the other guys have raised money beyond techstars, launched, or gotten traction, then you can do a less even split. In general, just having the idea isn't worth anything on its own. The hard work is to build the product and get people to use it.
1. The easiest and most common thing is to split all the equity now and figure out how much to fundraise later.
2. Yes. Standard is over four years, the first quarter of the equity cliffs at one year.
3. Most common is splitting equally. But this is really up to you. If you think the business guy is a really impressive person, worth four times what you are, then go for it. But this could be years of your life you're talking about. It's reasonable to say that you're only interested if it's an equal equity split - most of the work is still ahead of you.
As I understand, you typically raise funding just by creating new shares. There is usually a bunch of shares to cover options you're giving your employees, though ("option pool", something like 20% appears to be common); you may or may not be able to defer giving options until you raise money. (In the case of funding, you keep n% of the pre-money value of the company; in the case of options, you keep n% of the value of the company.)
Equity vesting for founders is a good idea, and very common. (If the developer quits in a month, you don't want him to own 25% of the company.) The business guy can make a case that he should have accelerated vesting, since he's been at it for longer. Cliffs are possible ("no shares for the first year"), as is accelerated vesting on change of control (basically, you get your shares faster if the company is sold; this makes it easier to leave, which is bad for the buyer, which lowers the price (s)he'll pay; so this is somewhat hard to negotiate.)
The "fair" distribution of shares depends very heavily on what everyone brings to the table; you may want to "Ask HN" with more details. (For 60%, he'd better be good.) (EDIT: also, if he just wants to be able to out-vote both of you, you can easily create a class of shares with extra voting powers.)
