First time Self-Employed Quarterly Filing

1- For individual contractors or self-employed individuals, is the tax bracket for gross income on Form 1040 determined based on yearly income or monthly salary?

 

2- Where can I access federal income tax calculators and Massachusetts tax calculators for consultants? I have low business expenses how will that impact the overall federal and state tax I will owe at the end of year 2024?

 

3- My estimated gross income before taxes and deductions is around 130,300 for 7 months under my current contract. Is this the correct amount to use to determine my tax bracket ?

 

4- On my schedule C how do I calculate my miles ?

 

Thank you