Here is info about stock options based on my experience from several VC-backed companies, of my own, and of friends.
There are three chunks of stock in any startup:
I prefer two equal cofounders, with same stock and comp plan as each other. Building a startup is a ton of work, and I think it works best - and drives founders the hardest - if they are equal partners. If one founder started before the other, the way to deal with this is with vesting schedule, not with giving the second founder less equity. Unless the second founder starts after a team has been hired and there is a product and customers, at which point the newer cofounder should get less equity than the original founder.
Most VC-backed technology companies will "vest" your stock monthly over four years, with a one year "cliff". The cliff means that if you leave before your first year anniversary, you get zero stock.
Incentive Stock Options (ISOs) are called "options" since you have the option of "exercising" (buying) the stock each time it vests.