Great questions, @abilityto.
Personally, I would (and do) have separate sheets for business and personal accounts. You can unify your feeds under a single Tiller Money subscription, but I’d recommend creating discrete spreadsheets and only linking the accounts that are relevant into each one.
Regarding your TWO businesses, unless there are overlaps (e.g. credit card payments) or efficiencies in putting them together, I’d recommend creating a discrete spreadsheet for each— especially if the Categories are different. The Business Dashboard, for example, will only work well with a single instance installed in the spreadsheet (making it difficult to manage two businesses.
Hope this helps.
Randy