Building my first medium sized network Update. Need more advice, better diagram

Previous post: http://ift.tt/2CojOWA Like I said before, Ive got a decent amount of IT experience but I dont want to buy the wrong stuff, especially since we're on such a tight budget.

This is what the office actually looks like: http://ift.tt/2zN7tsg (Legend: Yellow triangles are 4 or 8 port switches, green stars are printers, blue lines are ethernet wires and green lines on the walls are 2 ethernet jacks. if they have a red dot on them they arent working)

I left out the individual lawyers offices because they all work fine other than being on a slow network and they all only have a single pc in them.

Anyways, we got about 40 computers, 40 phones and 10 printers on this network as well as a shitty NAS and a dell server of sorts The router thats actually doing the business is a microtek rb3011uias-rm. The 48 pt switches are cisco catalyst 3560 100mpbs max. They are not set up at all. There is also a random netgear nighthawk x6 ac3200 that i probably will move and use as a wireless access point.

The goal of this network is for everyone to be able to access their files (photos and pdfs mostly) from the server and run their software (its called abacus, its law firm management software)

Now I know one of the biggest issues is the room with 12 computers in it that has only 6 ethernet wall outlets and several cheap 4 port switches daisy chained together. Should I just throw a switch in there that can handle all the connections and call it a day, especially if I get everything up to gigabit speeds or do you think I need to do a drop for every computer in there?

Here are the questions I have now: Is the server room wired correctly?

What can be done about the room with 12 computers and 6 ethernet outlets? 1 good switch or do I need to do drops?

How much of a help will upgrading to 1gbps switches?

In the last thread people kept telling me to set up VLANs for the phones and the computers so they were separate. Will that be a big help or not really?

How do trunk lines work and does that make 2 switches act like 1 switch?

What kind of 48+ port switches should I buy?

Lastly, the dell server is running win server 12. Active directory is not installed and the server isnt really doing anything. How do i go about making active directory work? is there a guide thats good for someone starting from scratch to set it up with group policy settings and accounts and such?

thanks so much in advance! You guys have been a huge help~!