Quote from lindq:
If you form a corporate entity, you'll be paying a lot more in taxes.
The greatest advantage to filing as a trader is that your income is not considered to be "earned income". So you pay no self-employment tax (a big savings), or social security.
If you pay yourself through an LLC or other corp structure, you are essentially "salaried" and earning income, for which you will be taxed and pay Soc Sec.
On the other hand, a big advantage to setting up a corp is that you can establish some nice retirement programs. If you can earn good income for a long period of time, that is an advantage.
Each direction has pros and cons that have to be carefully weighed by a good CPA, based on your expected returns and long term goals.
Regarding deductions, it makes no difference with either filing status. You should not fear to deduct anything and everything that is appropriate.