can you be incorporated and still have sole proprietorship?

Answer 1

No - you are one or the other

Sole Proprietorship = unlimited personal liability

Incorporation = well, its complicated. If you are a sole shareholder, you will most likely not have much protection. The corporate veil will probably be pierced.

Answer 2

No. By definition, SP's are unincorporated. You will need to check your state's statutory code for the specifics, but SP's are nothing more than an individual, you file one tax return (your business income is just on a different schedule), and there is no separate legal entity. Incorporating, by definition, creates a separate legal entity.