- Do updates show immediately (for both directions)?
- What are the limits of read/write queries?
- What are the limits of rows?
- Can I use formulas in the sheet?
- How is the type handling? Does everything get treated as text or are there date and number types?
- Do formatting options for columns (e.g. for number of decimals) survive when I alter things with the API?
Yes, changes are apparent immediately.
- What are the limits of read/write queries?
The details are mentioned on https://steinhq.com/pricing.
- What are the limits of rows?
Details available on the pricing page as well. A thing not explicitly mentioned is that you can add any number of rows to a sheet. In append operations, the row limit is not checked.
I'll let you know the other details soon. That's something many have been asking, and I'm deciding what the default behavior should be.
Everything is converted to JSON over the API, so it's all just text and numbers.