It will be one formula per column always. This is a good thing as it takes away the Sheets chaos...
Now to do math like above, you just create column A with free number input, column B with free number input and column C with fixed formula A * B.
If that math is not sufficient you create additional field D "Calculation type" - with single select containing "Add", "Substract" or "Multiply by 3 and deduct 1" and then you upgrade the formula in column C to something like:
"Multiply by 3 and deduct 1", (A+B)*3-1
No you cannot do this in Airtable. One of the differences between a spreadsheet and a database is that each editable cell value should be an “atomic” value, the smallest piece of meaningful data. When you have an expression like 1+1, you have multiple bits of meaningful data that you want to combine. If you find yourself wanting to do this often, you might want to revisit your base design.