Quarterly taxes & payment methods; business checking accounts

Hi! I officially started a sole-proprietorship this year and my spouse has W-2 income. Last year we used my spouse's W-4 to withhold more money to cover my business taxes. We still ended up short and incurred an IRS penalty. This year I wanted to try paying quarterly taxes, but missed the 5-day advanced registration deadline for paying 1st quarter taxes via the IRS's EFTPS system. So I used the IRS Direct Pay instead. My question is: as a business, should I officially register and use the EFPTS system, or can I continue to use the Direct Pay System?

 

And a second question: do we really need to set up a formal business checking account at a bank (where you show your business license etc) or is a separate personal checking account sufficient? I contributed toward a SEP IRA last year and my understanding is that *ideally* those contributions should be transferred from an official business account. Thank you so much!!!!