How can I create a library of forms clients can complete and email to me and save their answers for repeated future use

I am an attorney and need clients to fill out multiple PDF forms.  Information is repeated across forms (like property address and tax ID number) and needs to be saved to make the client's job easier when they fill out the form next year.  And, if clients have multiple properties, each property will have its own universe of data that should be saved for use in the future.  Then, when the client completes the form, I would like to have a button so they can click and email to me.

Also, does JotForm have a list of experienced developers who can help me set up these forms using advanced features?

There is a way for previous form respondents to get back to the submitted form even after a year they had submitted it.

The user can re-submit the form later.

Check this user guide on how to. 

-How-to-Let-Users-Update-Their-Form-Submissions-at-a-Later-Date

The user can go back to their submissions, change/update information, and then re-submit the updates/changes.

Let us know if this cannot work for what you need.

Also, does JotForm have a list of experienced developers who can help me set up these forms using advanced features?

We do have such developers, but you need to tell us which advance feature you were referring to here and perhaps we can relay them to our dev team.

Thanks.