tax questions

[Dave2020]

I have a few questions and would greatly appreciate any help in answering them...

1 - Roughly 85 to 90 percent of my income in 2006 came from online poker; the rest came from working for a friend in the construction business. Am I REQUIRED to file as a pro using schedule C?

2 - If I file as a pro it will be my first time filing this way. I have not payed any quarterly taxes on my 2006 income because I was unaware of my responsibility to do so. Can I avoid a penalty on the basis of not having any previous records to base quarterly payments on?

3 - If I don't file as a pro, am I still obligated to have already made quarterly payments?

Thanks!