I use Mighty Networks for my community and love it. It has many features that Facebook Groups/Slack has, but is very customizable and you can enable members subscriptions and make money on day 1.

I use Xero accounting software and it's very user friendly. They have an add-on marketplace you can connect different services to likes stripe, Expensify, Shopify, etc. 100% paperless. Do taxes myself, just print out a P&L from Xero and populate in H&R Block tax software.

Ask: "what's the biggest challenge you are currently facing?". That'll give you a look at your members pain points.