If new web form campaign is sent out can I then after send URL of this page to other customers?

Once a new web form is sent out can I afterwards send a URL of this page to other customers I work with so they can sign up on our list easily?

Additionally, do I have the ability to validate the accounts in bulk before they automatically get pushed out to the full mailing list?

Yes, you can send the URL of the web form to anyone that you want to sign up to your mailing list.