Help Needed

We are planning to move to OSticket.
We will need some help to evaluate if:

we need a hosting or a vps server instance
spam and correct email settings for sending
Firewall settings

We are a small team of 8 persons but we are not all day working against Osticket.
If someone with proven records could help us would be great.

Doesn't matter but typically you'd want a server you can control and is not shared with someone else so you can make whatever changes needed.
Don't know what you mean by this. Can you provide further clarification?
Firewall settings are entirely dependent on your needs and completely out of the scope of the software. For this you'd need to do your own research on whatever platform you acquire.

Cheers.