Can I use a non "me.com" address to send email with iCloud?
Using iCloud doesn't necessarily means you'll have to use Mail on iCloud. You can still use your current mail provider to send/receive email on your iPad. Providing you can connect to your current provider using IMAP, Exchange or POP.

You can also create your iCloud account without having a @me.com address. I use my @gmail.com address as my Apple ID to connect to iCloud to sync Contacts, Calendars, etc.