Changing DNS servers and Email problems

I currently host a domain I wish to use with CloudFlare at Freehostia.com

I use this domain for emails

Simple question please: If I change the DNS servers to CloudFlare but leave the domain hosted at Freehostie.com, will it affect my email addresses?

Yes, that is if you use the proxy settings of Cloudflare (orange clouds). If you leave those off (grey clouds) they will be like normal and won’t interrupt the email in anyway.

I’m trying to assign an MX record to my domain at Cloudflare. I am being prompted to add a priority to this which ranges from 1 to 65535. Which do I use?
Any help would be greatly appreciated

Sorry I didn’t see you had replied.
Normally a value between 1 and 10, doesn’t really matter if you only have one or two MX records

Many thanks:-)