how to have seperate contribution pages for each membership type.?
You can create 3 contribution pages, each having single membership type(selected under Memberships tab of contribution page) and set it to default and change the link(boxes from the screenshot) to use respective contribution page. 

To hide the option you can use JS or CSS.



For emails not getting send make sure you have configured everything correctly like
1. Postfix package
2. From address in CiviCRM (CiviCRM >> Administer >> CiviMail >> From Email Address)
3. Updated the default mail accounts (CiviCRM >> Administer >> CiviMail >> Mail Accounts)
4. Updated Organization Address and Contact Info (CiviCRM >> Administer >> Comminications >> Organization Address and Contact Info

Probably looking  in Civi or CMS or apache logs for any suspicious errors might help to find the problem. 

HTH

Pradeep