In every place you put "virtual machine" in your question above put "computer" and for "host machine" substitute "server". Now answer the questions yourself. The point of "virtual machines" is that for most purposes they are indistinguishable from "real machines".

The more interesting problem is code management. Should you keep a single copy in a common place or have a copy on each machine and a system for deploying changes? That is not something we can answer without knowing more about what you are doing. Whatever you do I'd strongly advise you to use Mercurial or git to revision control your code.