Subscription services

2. Consent :
We currently have 'Contact form' on our website. We need to take consent of a person to contact him / her to resolve their queries (for which they are contacting us) and send him / her periodic updates about our products and events etc. We may be sharing their data with third party marketing service provider in case they opt for receiving periodic updates. Our privacy notice talks about third parties. Is it okay to give reference of our privacy policy in the consent form ? Instead of having a long consent form can we just ask the user to refer to privacy policy for details such as data shared with third parties ?
3. Revoking the consent to send emails with periodic updates - We do not provide facility of creating user id etc on our Website. Based on data collected from contact form, we send newsletters and product updates. We have an 'Unsubscribe' option in periodic updates email that we send.s it necessary to provide 'Unsubscribe' option on website also - e.g. should we have a link