We are currently using yahoo webhosting and yahoo plus (paid) mail, and wanted to use Zoho business, mail and CRM, but before we go fully loaded into Zoho I wanted to make sure I have following answers to have business continuity:

1. Once we configure the mail with zoho mail , can we still receive mails using yahoo pop?  Basically don't want to make any changes until we have proof this is going to work.
2. Can we copy all the mails we have in yahoo (paid) - mail ? we have about 6 years worth of emails?  How is that going to work?  how much storage space we need to buy? we have about 30 Gig of emails?
3. What about webhosting? can we keep it with yahoo for a while and then switch? 
4) I currently able to view my yahoo domain name emails on iphone and blackberry, will that be still possible? do I need to do anything else.  In otherwords, I don't wanted to make any changes to my existing settings, but wanted to receive my emails in Zoho mail.


Note: In the attached snag from yahoo, they are stating that, if I set our MX record with priority anything less than 50 mean, our yahoo account become inactive  - is that answer my questions above ? I can not have both or is there a way to get it ?


some clear answers to these will be helpful.

Thanks,
for Druv