Quote from Robert A. Green:
That's why we recommend S-Corp elections for SMLLCs, so they are separate tax-filing pass-through entities. The SMLLC S-Corp can pay the owner a fee or salary, to financially engineer some earned income to unlock AGI deductions. S-Corp elections can be filed late with Rev. Proc. relief. But, S-Corp 2012 extensions were due March 15, 2013 and the late-filing penalty is $189 per month, per partner (which is just one partner).
A Schedule C trader - sole prop whether SMLLC or unincorporated - can not pay themselves a fee.
I believe you can file LLC return the same way as a multi-member LLC, like a S-corp or partnership. This is why LLC is so flexible.