Back accounts

Yes you can use your personal bank account or credit card to pay self employment business expenses.  What "incidentals" are you talking about?  You need to fill out schedule C for self employment.  Are you new to self employment?

To report your self employment income you will fill out schedule C in your personal 1040 tax return and pay SE self employment Tax. You can enter Self Employment Income into Online Deluxe but if you have any expenses you will have to upgrade to Premium version. Or any of the Desktop programs. But you will get the most help in the Home & Business version.

How to enter income from Self Employment
https://ttlc.intuit.com/community/self-employed/help/how-do-i-report-income-from-self-employment/00/26653

Where to enter business expenses
https://ttlc.intuit.com/community/entering-importing/help/where-do-i-enter-my-self-employment-business-expenses-like-home-office-vehicle-mileage-and-supplies/01/27109

Self Employment tax (Scheduled SE) is automatically generated if a person has $400 or more of net profit from self-employment. You pay 15.3% SE tax on 92.35% of your Net Profit greater than $400. The 15.3% self employed SE Tax is to pay both the employer part and employee part of Social Security and Medicare. So you get social security credit for it when you retire. You do get to take off the 50% ER portion of the SE tax as an adjustment on 1040. The SE tax is already included in your tax due or reduced your refund. The SE tax is in addition to your regular income tax on the net profit.

Here is some IRS reading material……
IRS information on Self Employment
https://www.irs.gov/businesses/small-businesses-self-employed/self-employed-individuals-tax-center

Publication 535 Business Expenses
https://www.irs.gov/pub/irs-pdf/p535.pdf

Turbo Tax Self Employed Tax Hub
https://turbotax.intuit.com/personal-taxes/self-employment-taxes

Turbo Tax Self Employment info
https://turbotax.intuit.com/tax-tips/self-employment-taxes/beginners-tax-guide-for-the-self-employed/L2HLojrj5