Hi Amey
I hope you are well and many thanks for using the SAP Discussion Forums .
Ok you have quite a few questions here so lets see if we can work through them together .
Scenario: You need to migrate from CE7.3 EHP1 SPS9 Portal to CE7.4 Portal and would like to know comments/suggestions/experiences on this particular scenario.
Regarding your queries and comments the answers to these can be found in the following documentation which has been developed in a bid to provide an informative overview along with a comprehensive guideline structure.
Upgrade & Migration Approach 7.3
http://scn.sap.com/people/sushil.aher2/blog/2012/02/14/sap-nw-73-portal-upgrade-approach
Migration Lessons
Also the below blog post:
Kindly review the documentation outlined above and if you have any more questions please feel free to ask me.
Kind Regards
Troy Cronin - Enteprise Portal Support Engineer
Follow: @troycronin