Where can I find the campaign id/email id in Marketo
Campaign ID is automatically populated in the token {{campaign.id}}.
Email ID is parseable using Velocity, but as Michael mentioned you can also manually copy it from the URL. I don’t know if that’s very maintainable, though, as when when you clone an email the ID naturally changes.
Also, do we just have a filled out form filter in the smart list with date of activity and query string constraint? Or will it be good to also add clicked link in email in the smart list logic?
Clicked Link in Email is not necessary. That’s why you tag links with UTMs or other identifying information, so the visit is known to be from an email click.
is adding mkt_tok mandatory since the value seems to be unique to each link in the email. I have several emails to track form fills for.
Don’t know what you mean here. You never add mkt_tok anywhere in the Marketo UI. It’s automatically added by Marketo.
You can learn a lot about mkt_tok in this post: https://nation.marketo.com/t5/product-discussions/how-marketo-identify-and-merge-the-database-with-page-visit/td-p/309975