so when tiddlywiki loads this table, it creates tiddler with this google form, an this form send orders to other spreadsheet, and this spreadsheet send e-mails to shop and customer.
This Russian
video shows how people can create their free online stores.
1. Yes every line of every worksheet is a tiddler (id=title, name=caption)
2. No, now it is not possible to modify spreadsheet through Tiddlywiki, But in future (I hope) I will write googlescript hook. Spreadsheet can receive POST ang GET with password and commands what to do with spreadsheet, so it wil be possible to add and remove lines, look for tiddler by id (title) and modify it. May be tiddlers will be in JSON, not to create many colons.
3. You can test it. It will be created, but you will not see it in spreadsheet/
6. All images are stored on Google drive (or on your hosting if you want). Script in spreadsheet reads folder's content (I use _images folder). And put all titles of images and their path ID to GD-images worksheet (if you press a button). So Tiddlywiki loads this worksheet too, and you have all
images from _images google drive folder in your store
7. There is no limitations to spreadsheets read (or they are very high) I have never reached any limits. Limits has only google developer console, but i don't use it. The only limit I know, that you can send only 100 emails per day through the spreadsheet.