C vs. S corporation is a tax issue that you should discuss with your tax advisor; the fact that the business is Internet-based is not germane.
You might want to look into whether an LLC or a corporation is better for your situation; please see Should I form an LLC or a corporation? While you can form your corporation (or LLC) in any state, you might as well form it where you are located, because that is where you will be considered to be doing business. Please see Why (not) incorporate in Delaware and Why (not) form an LLC in Nevada? Disclaimer: This post does not constitute legal advice and does not establish an attorney-client relationship.
Have you considered an LLC? An LLC gives you the liability protection of a corporation with the flexibility to choose the tax structure that best suits your situation, all without the extra paperwork required by a corporation.
I suggest you read about these differences before talking to a lawyer. You’ll know what questions to ask, and it’ll cost you less. There’s a lot of information online about this. I would start with the Nolo website. They have a lot of good, accurate information. Nolo also has a book that may help you, LLC or Corporation? How to Choose the Right Form for Your Business. I haven’t read the book, but I have read several other Nolo books and they’ve all been really good.
Yes, you can register your company in any state. However, you probably won’t get any benefit out of registering in a state other than your home state. If you register in a different state, you will still have to register your business in your home state as a foreign entity. Of course I don’t have all the details. You may want to talk to a small business lawyer about this.