If you file joint tax return and you have a refund or even you owe taxes, but the amount you owe is less than $1000 - you do not need to file the form 1040-ES during the year and do not required to pay estimate taxes.
As you file jointly - adjusted gross income from joint tax return should be used.
Yes - that is correct - you are not required to pay estimated taxes.
If you do so - you would be receiving larger refund...
But if the business will grow - you need to estimate your future tax liability based on net business income - self-employment taxes 15.3% plus income taxes based on your marginal tax rate (normally 15% or 25%). If additional tax liability will be more than your normal refund - you may need to pay estimated taxes.