Migrating PHP/MySQL based website to cloud server

I have a web site developed in PHP/MySQL and hosted in normal webserver, so far there is no issue except in rare cases hosting server getting down for few hours. Now client wants to host the same site in cloud server. (My site is something similar to churpchurp.com)

My Question is,

What are the changes I need to do in the code when I move to cloud server.
My MySQL database will be same or needs to change (including my existing data).
Is it good idea to move to cloud at this point of time for this kind of website.

Please help me to decide.

Solution

I am new to cloud technologies, Just like many I know the cloud is hsoted by Amazon and other providers and is more reliable and scalable

It's is not more reliable and scalable if you don't know how to use it. If all you do is host at amazon you get the exact same result as hosting anywhere else. Those scalable and reliable (i.e. distributed) technologies require you to know how to use them. Explaining how to do that is far beyond the scope of this site.

I do not recommend hosting on "cloud" server until you learn a LOT more about the technology they use to spread out your app on multiple machines.