Questions about a Side Gig (1099 Income)

Hello, 
I have a W-2 full-time job but also earn side income through teaching aquatics training courses for various city pools. With this side gig I have to fill out 1099s. I have a few questions because of this: 

1. Do I need to pay quarterly estimated taxes? How much and when? 

2. What should I be tracking for deductions? 

3. Should I open a separate bank account for my side gig? 

4. Would forming an LLC help me save on taxes? 

 

Thank you!