Setting up Opmanager - servicedeskplus environment

Hi all,

We just bought Opmanager & servicedeskplus.
What are the best practices?
We can install it on a physical server or we can create a vm on our vpshere 5 farm.
In case of failures, opmanager must run as long as possible, to keep sending alerts.
In that case, I think installing it on physical machine would be better.
Our central sql server is a vm in our vsphere 5 farm. So what if the vmware farm goes down?
Can opmanager send alerts, even if the sql server is offline?
Or is it better to store the opmanager database on the local server?

We also want to implement desktopcentral. Can we install opmanager, servicedeskplus and desktop central on 1 server if specs are ok?

Thx for advice!