The only requirement for ZERO downtime transfer of your website is that you do not delete your current web hosting account, until your new hosting account is set up.
If you want to transfer your hosting to india.to then first you have place an order for hosting and make payment. After that there are two ways to transfer your data:
No, you cannot move large files as it will causes problem. So it will better if you manually upload data through FTP in your new hosting account.
No, on windows server you have to manually upload your files in your hosting account through any FTP software or plesk.
No, there is no need to transfer your domain here. After transferring your hosting you only have to change the domain's namesever at your domain registrar end and the nameserver given by us.
Account will be activated immediately after making payment.