I have read a lot of documents but for some reason I can't figure out what we would need to deploy Microsoft Team Services at our company. We can't figure out if we need Portal or not, Services is definatly better then what we have now.

Here is an overview:

Right now we have about 250-300 employees it won't grow more then 400-500 in the next 5 years.
Hopefuly we could get users to start publishing docs on here like they should vs cluttering our shared drive up as much as they do.
I would think that two servers would be more then enough. One server would host the website and document storage while the second would host SQL. I just don't have experience on how much performance we will need. I don't want to implement this and it be laggy.

Also we really are indecisive about Portal Server. Obviously cost is the biggest factor. I believe that Portal will index network files to allow docs on shared to be searchable from sharepiont and services does not allow that. There are others but I believe those are the biggest.

If we end up moving to sharepoing ( I am sure we will) we will probably bring in a consultant because I want to make sure it is implemented correctly and we have the right backup schema implemented. Right now I have it running on a test box for our departmental use but I am afraid to set it up for the entire company. Here are things I am worried about:

Making sure documents, sites, database are all backed up in case something happens.
How hard is it to administrate when you start having departmental sites etc.
How hard is it to keep the documents in order? Two years from now I don't want 50 gigs of docs that are never touced.
Departmental sharing of data/docs. (what if department A needs to share documents of lists with department b?) It seems like it could be a nightmare trying to educate users on how to use sharepoint correctly and what "layer" certain things need to go.
Maybe I am overthinking everything but it seems as if sharepoint could become an administrative nightmare.