Getting started on the map is a chore. Even if you have css, the navmesh will not be included so you'll need to make one. This can be done by opening the console and doing the command nav_analyze. After the map reloads, enter console again and type nav_generate. This should make one for you. However, none of the doors will be properly locked so zombies can and will get stuck behind unopened doors. If you don't want that, you will have to do this yourself using the nzombies creative menu. After all that, you can finally begin playing. (spoilers for the map layout ahead, read if you get stuck or are curious about map layout)
When starting, the hallway you begin in will look like it's totally blocked off. You can continue by shooting out the window and crouch jumping out.
There is a very wide variety of wall buys. Most of them are very cheap too. I found myself not using the box because I could get very powerful rifles off the wall that were cheaper.
Perk locations are very strange. There are about two machines for each perk spread around the map. I assume this was done because of the restrictive layout of the map that makes backtracking to previous perk machines tedious and even impossible in some cases.
It is stupidly easy to get overrun if you make a mistake. Since there are limited pathways you can take, you cannot escape easily if you find yourself overwhelmed so make absolutely sure you can hold an area before deciding to camp. There is only one good trainable spot on the map that I know of and that is the courtyard at the back of the garage where the FAMAS is located. Even then it is very easy to get cornered so be prepared to ditch when that time comes.