Hi Raj,
Are there any changes to the “temp collection”? If not, why do you need it?
You can connect the repeaters and galleries to data without saving it in the browser’s memory.
I’d recommend you to check out more about the browser’s storage. check out this thread about the local and session storage.
As to your other question, there isn’t a limit for submitting data to a collection.
Anyway, you can create a temporary collection for each user using the session storage.