ThemeForest has some fairly restrictive licensing terms on their designs. If you are doing a small site that won't make you much money then of course this is the best route. If not then exploring Bootstrap designs from http://wrapbootstrap.com and looking at a fully custom design from http://99designs.com might be your best bet.
I always recommend that entrepreneurs form a company before they build a product. Everyone needs some equity up front for the work done to date. This equity is given in exchange for the company to take ownership of all the technology built today. The rest needs to be allocated to everyone (even you) on a vesting schedule. The end goal being that after the vest period the equity is evenly distributed. Vesting schedules have cliffs that distribute shares. Typically I recommend a 5 year vesting schedule with 12 month cliffs. If someone works for 11 months and vanishes you don't owe them any of the unvested equity in the business. If they leave after 1 year and three months they only vested the first year of equity on the schedule.
The issue at hand is that none of these roles is ever really done. It's very likely that someone will up and vanish for one reason or another while the company is being built and the remaining founders will have to bring someone else in and offer them equity to pickup where the previous person left off. Ensure you have take with and come with provisions for the protection of all shareholders.
Details: I would form the company as a corporation in Delaware with more shares allocated than distributed. Base your vesting schedule off of the shares allocated and not the possible number of shares distributed. This gives you the ability to sell shares to investors without having to pay a lawyer again in the future.
Source: Done this a few times and sold two companies in the last six years.
Me - http://www.strapr.com - happy to provide more advice if you want some, my email is on there.
Disclaimer: I am not an attorney and this is not to be construed as legal advice, you should seek counsel for your needs.