form with repeater, google sheet and more

I would like to create a form with repeater.

The data should write to the DB and also to google sheet, while each row should be a row in the sheet.

What is the concept of creating the repeater and how should the data be looped through unknown number of rows and create these rows in Google sheet?

should I loop in CF each row and write to the Sheet or send all the data and loop it in the sheet script?

what happens if another form is submitted while writing the rows to the sheet?

which joomla and CF should I choose? I know CF5,6 and some basic CF8.

I also need to save each row of the repeater into new row in the database where each field goes to it's designated column.

Is it possible to create a custom SQL ?