Hi Prabaharan,
1. Can't comment on it - only someone from SAP can tell something regarding this
2. SAP HANA 1.0(C_HANAIMP_1) - i would suggest that if you are a ABAPer you can wait for sometime for a certification regarding HA400
As you can see here:
https://training.sap.com/gb/en/curriculum/hana_uk-sap-hana-appliance-software-uk-en/
HA400 is standalone and if you go to related courses and Certificates tab it mostly shows ABAP courses.
From an ABAP point of view what you should know about HANA is - How HANA works and Data Modeling in HANA
But if you are also interested in learning SAP HANA and want to go for certification - then you will have to learn a lots of new things : Data Provisioning( SLT, DXC & BODS), Reporting(BOBJ, Lumira), Users & Authorization, XS Concepts( JSON, JavaScript, JQuery, SAP UI5, OData)