forms dependence + some more question

Good day to you
I'm thinking to transfer from wuffo to your services but i need to know if you support some features i need in my site that i know wuffo don't support it:

first i need to make 2 forms : registration form and payment form.

1. i need to have in the registration form in the username field and in the password field the option to enter it twice to make sure they entered the same email and password (like in all the registration forms in other regular sites) - is it possible?

2. after user enter his registration form he can go to the payment page and there he must have username (from the registration form) - what i mean, i need an option that after the user enter his username and choose the credit he wants to buy and press buy , it can check that the user already filled the registration form before he made a payment (i will have the same username field in both the forms and the payment form need to check that he have the username in the DB before he transfer to paypal and if not it transfer him to the registration form .

3. the last think is with the DB - is there a way like in wuffo (they call it webhook) that all the data that entered in the forms go inside my server DB ? (in the registration form) and also to update the Credit DB after a user making payment

hope you can help me here and i would love to be your developer customer

thanks

thanks for your answer but it seems i didn't got the answers to my questions so maybe i will try again to explain my self :

2. like i said i need the option to some dependence between to inputs in 2 forms.
i would like that only a registered user can buy credit.
for that in the payment form the user need to enter his username and his password.
both of them are in the registration form.
the steps i need :
1) the user go to the registration form and open up an account (fill up the form)
2) the user will get a mail with his registration details.
3) now the user go to the payment form and enter his username and the password and choose
numbers of credits he want to buy.
4) now when he press "pay" the form check that we have his details (his username and
password) if we have his details and he entered the right password he will go to paypal and if
not he will get a message tell him that we don't have his details and he need first open up
an account