Questions about DBA, LLC, and SubchapterS/S corp.

[NOC09]

I want to start an internet business as a sole proprietor (for now) in California. This business will be based off fitness information products offered via website.

Would setting up a DBA be the better choice than setting up an LLC?

I've read in a business book that as a sole proprietor, the IRS will recognize you as one entity.
Other than reporting business income, losses, expenses, etc. on your individual tax form, what are the benefits of doing that?
Wouldn't it be better to make your business separate from your personal assets in order to limit liability?
Is it possible to separate your business entity and personal assets via DBA?

From what I've read: the only disadvantages that may concern me are the tax disadvantages if I end up having high profits (whats considered high profit?) and the personal liability for any screw ups on my part.

In the case that I do make high profits (God forbid ), would a transition from DBA to LLC be easy in terms of keeping the same business name? Are there any other difficulties I should be aware of?

I'll be selling information products in regards to fitness. Should I really be concerned about lawsuits? Wouldn't a product disclaimer / do at your own risk type of warning be enough to prevent this? I mean if I bought P90x dvds and hurt myself its not like I'm going to sew the company. Now if I were selling a physical product, I assuming an LLC would be the better choice.

[NOC09]

Oh and should the subchapter S, which I'm assuming to be for LLC, be a concern to someone (like me) who isn't making any money yet?

[LLCtaxes]

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