can you please help me to clarify some questions on the pricing tiers?

Could you help me clarify the 10 payments for the free account. Does that mean once we have more than 10 applications, the account will not accept any payment? Are there additional fees on payment transactions? In terms of the 100 MB available space - is this for each submission or is this the total amount of data that is stored? what happens once this space is filled - will applications still be accepted? 

Free accounts can receive up to 10 payment submissions per month.  Those are submissions that also collect payments through one of our payment processors:

https://www.jotform.com/help/47-Order-Form-Basics/

If you exceed that limit, after a about a day all forms will be disabled.  The same goes for exceeding any limits.  Form can be restored after that point by upgrading or when the monthly reset occurs on the first day of the next calendar month.  There are no additional fee's from our end for payment transactions.

The 100mb limit refers to files uploaded and stored through forms.  This is a total across all forms.  This total can be reduced by deleting submissions that have files uploaded with them.  If this limit is exceeded, the same will occur as any other limit.  Forms would be disabled.  However, with this limit, forms can be restored simply by deleting submissions to get back under the limit.

If forms are disabled due to being over limit, they will not accept new submissions.