[q0192837465]

I've tried Google and I can't really find what I'm looking for.

Background:
So I started this new job in a small accounting firm. We have 3 ppl in total, including me. The office already has a server. However, this server is shared with a former partner. Therefore, we have effectively 2 separate companies sharing the office and the server. Even though we highly doubt there will be security issues, it is still good practice to keep client's info physically separate. This is why we need a new server set up.

Problem:
For some strange reason I was asked to find out how to build a new server. My computer knowledge is alright at best. I have done some research on Google but I can't seem to find exactly what I need. There is no tech guy in the office so if something goes wrong we have to call someone in. It is highly unlikely that we will have more than 5 ppl in the foreseeable future.

My understanding is that I need
a) a computer with a big harddrive (i dunno what OS to run)
b) router
c) cables to connect to all the computers

Like I mentioned earlier, even though security is not really an issue, it will still be important to setup good security measures just in case someone file a lawsuit against us. Also, we would like to be able to share calendars (thru outlook I believe) in order to schedule meetings.

Questions:
1) Do you guys think it's do-able or is it gonna be a complete nightmare?
2) What is the approxmate cost of building such system, excluding labour (a 2-4 TB storage should be sufficient)?
3) How much time will it take to start from scratch?
4) How much work is needed to maintain a server (hours/month)?

I mean if it's gonna be hell then I'm just gonna tell the boss that I can't do it.

Sorry for the long read.