Poker, the IRS, Law, and Self Emp Tax

[mo42nyy]

The real [censored] up thing is if they make you retroactivly file as a pro (a few years after the fact) you cant then go back and make sep ira/solo 401k contributions for those years.

I made a post earlier about not being sure whether or no I should file as a pro this last. Last year i did ( iplayed poker for about 310 days of the year) but this year Im not sure if I want to as I have almost no deductions, barely played after neteller went to [censored], yet made about 4-5 times
more than what I made in all of last year.
if I max out a solo 401k Ill pay almost the same exact ammount of taxes either way, but
1) Im not sure if I wanna sock all of that money away for 30 years
2)I may want to file as a pro again in the future as I will be playing live a lot more and consequently have more deductions.and Im not sure how not filing as a pro this year would affect that

What would affect that greatly is the following set of questions:
Are you even allowed to deduct a mortgage on a co-op?
If I buy a coop studio aprtment on which I take out a mortgage (payment would be about 400 a month) can I deduct
the mortgage and monthly maintaiance fees (about 300 dollars a month) on schedule c (proportionatly for a home office of course-say 40%) instead of my schedule A?
The reason I would want to do this is that the standard deduction is 5300 (and climbing while the mortgage payments stay the same) so taking it as a normal deduction would be worthless. However deducting it the payments on the sced C would save me a great deal in taxes. Do you have to take your mortgage deduction on the Sced A?

As for deprecation- would I be allowed to dedcuct depreciation on the co-op (i think over 27.5 years-proprtionally to the size of the home office) on the sced c as well?