Choose ubuntu lts (10.04) 32 bit, 64 bit uses more ram and you probably don't need it's benefits.
How "hard" something is all depends on your experience, confidence and set up you have.
In theory to move a database to a second vps you set up the vps, shut down your database, dump the database, restore it to the new one, change you web apps to point to the new server, start your new database and you're done.
Of course the more vps you have the more work it is to administer.
The
linode library has tons of guides on how to set up for various scenarios or you could hire someone to do it for you.
Email most people tend to agree for small setups it's a good idea to out source to somewhere like google apps if you plan on sending and receiving email.
For just sending email postfix and exim are easy to set up the library has guides.
You can have a dedicated VPS as a content delivery server but you might find cheaper solutions from a dedicated CDN.
FYI bandwidth is pooled across linodes.
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Paid supportHow to ask for help
1. Give details of your problem
2. Post any errors
3. Post relevant logs.
4. Don't hide details i.e. your domain, it just makes things harder
5. Be polite or you'll be eaten by a grue