Can I get actual submission date to populate on forms, rather than letting respondent select date?

Thank you for contacting us.

This is possible with a DateTime field configured with a Current Default Time.

Note that we also automatically include server submission time with each form entry.

Please feel free to contact us if you need any further assistance.

Can I prevent responders from selecting a different date?

@ bpprall

If what you pretend only is to get submissions with the current date that the DateTime field shows, do as follows:

Click on the gear(1), then select Hide Field(2) as shown below:

In your form builder the DateTime field will displays as follows:

I hope this helps.