4 questions about deductibility of credit card fees for small business owners

Hi,

I have 4 questions.  Please keep numbering in your answers.  Much appreciated!  

1. We have a small business.  I earn with W2 and my spouse earns with form-1099 for her small business PLLC sole proprietorship.  It appears per IRS that an annual fee for a business credit card such as Chase Ink is deductible.  Please confirm whether my interpretation is accurate. 

2. I pay extra Fed + State Taxes from my W2 to cover the business earnings but we still fall short every year; so we pay 1040-ES each year.  Say $10k/yr.  I noticed that for 1.87% fee, IRS accepts Credit Cards to pay the fee.  While it is not a small percentage, if we pay with a credit card, for say $10k we pay in 1040-ES, we will incur $187 annually just in fees.  I want to know will that be a deductible business expense for the coming year?  Which bucket under Schedule C will it fall under?  

3. After preparing 2019 taxes with TT, I find that we owe IRS ~$500.  If I pay that with a credit card, it is a payment against 1040 (not against 1040-ES); will that be also tax-deductible against the business expenses the next year?  

4. Is there a less expensive option to pay IRS with a credit card than 1.87%?  

Thanks!