Q. What type of queries to be run on postgres database server?
All types. Databases will be general OLTP.
Q. Size of commonly accessed tables, indexes, ... ?
Various. Anywhere from a few MB to over 100GB.
Q. Database size for current and for future for all databases:
Various. Anywhere from 100 – 1000GB and always growing.
Q. Total Connection limit from the database through users and Application on daily basis for all the database:
Probably 4000+
Q. CPU Core:
Prod databases will have 32 cores of CPU and 128 GB of RAM.
So, what's your question...? Given the broad brush generalities and explicit references to multiple databases I have no clue what you expect from this list - not that I was going to be of much help on the topic anyway...