I need to offer people the ability to sign a petitio

I need to offer people the ability to sign a petition, so we can use that (hopefully) long list to bring pressure on Congress, and even those specifically FOR or AGAINST certain issues. I heard that was still legal :)

Here is an example that I consider in the case where there is an investigation needed...

What fields of information should I consider requesting?

First Name

Last Name

Address Line 1

Address Line 2

City

State 

Zip

Party Affiliation (optional)

Check the box and sign below:

[X] I DEMAND AN INVESTIGATION into X, Y and Z 

JOHN DOE

__________________________

Name (signed - ALL CAPS)

Suggestions? How best to have someone digitally sign? Should I try and make a formal electronic signature? 

Any software tools I should consider?