Doubt's in redesigning

I have several questions out there

There is a client i want to change the design of website to brand new and use same previous domain name.

1.Is using previous domain name a must.

2.can i know procedure to get domain name from old owner of domain to me ?

3.only domain transferring is enough in that case to registrar of my choice which i am comfortable like crazydomains.in ?

4. can i use my choice host globehost.in as i will be designing it new ?

Please if anyone would clarify my doubts would be it would be great.

 

1) Its a good idea to use the previous domain that is already in use, but its not a hard and fast rule that you have to use the same. You can have a new name and redirect the previous one to the new domain (for seo and retaining the link juice, but you have to do it right).
2) You have to go through your new registrar there must be a webpage there that will allow you to initiate domain transfer from other host, once you initiate the process, it has to be approved from the original registrar cp to make that working.
3) Yes you can have different host and different registrar. You only need to make sure that the dns settings is pointing to the right direction.
4) check out 3 above.