Good news The first problem is solved.
For multiple signature blocks in the same form, you need to only have one signature pad per form page.
I determined this because I tested two signature pads on the same page 1 of the form. Only the second of the two signature pads displayed output. The first was empty.
Check out the demo for multiple page forms. All you have to do is add a page 2.
On the top of page 2 copy your css file from page 1 if you want your buttons and signature pad css to look the same.
Then Create a back to prev. page button by changing "submit" to "prev page".
Then add a submit button at the bottom of page 2 under the prev page button.
Bingo. Here is the output when I drew "1" on page 1 sig pad, and "2" on sig 2 pad.
Note that I left my db save and email in the Action for page 1. There is nothing in the Action of page 2. The form still processed. You would think that the Action had to be on the last page, but it doesn't and the form still appears to work just fine.
Forgot to mention.
The two blob columns in the datatable for the signature form, and the signature pads in the signature form - I named them "party-1-signature" and "party-2-signature."
Assuming the form was very basic, you also have to put this in your data save action for the signature form. Once the table matches the fields in the form, select the table name n the db save. Put {data:}, put {data:} in Data Source, "id" in primary key if that is what you are using, type out all the table fields in table fields, and in the modify data source put something like the list below for a simple form where these are the only fields.
Note this form is for already created and logged in users. (you need a DB read on the load event for id, user_id, username, name, and email from the joomla_user table.
FYI - The remaining fields I put in my own extra profile fields table (firstname, lastname, suffix, and you can add any other fields in that extra profile fields table to create your own profiles for the users. I then had to crate my own profile menu and webpage to display the entire user profile, and my own edit profile page. This is critical if you create extra forms to make sure that each extra form has a DB read of the Joomla user table, and a DB read of the extra profile fields - so that the latest user profile info gets called up and inserted into all other forms you create)
(The party-1-signature and party-2-signature fields plus all the other core joomla user core fields from the user table are all in the signature_form.)
This goes in your modify data source of the db save:
[FYI, these fields are from the user table]
id={data:id}
user_id={data:user_id}
username={data:username}
name={data:name}
email={data:email}
[FYI, these fields are from my extra profile table]
firstname={data:firstname}
lastname={data:lastname}
suffix={data:suffix}
[FYI, these fields are from this signature form only]
party-1-signature={data:party-1-signature}
party-2-signature={data:party-2-signature}
[FYI, all of the above fields are saved in the signature form and it's data table]