So first off, the three gnome locations.

The first one you can find after opening up to jug, go to the 2000 points door and look at that tall tower in the background, it will be on the right side of it. The tower is behind the building with the 5 perks/mule kick teddy bear.

The second one is after you open the door to speed cola, go up on the staircase with the 40,000 challenge/potatoes and look at the roof of the building ahead, there'll be a gnome lying on top of it.

The third one is close to Double Tap, go over to where double tap is and look between the two stone? blocks, there's a vehicle with a mounted gun there, on the mounted gun is a gnome.

You get 150 points per gnome and once you get all three you get the gnome protection, it's pretty damn handy if you're struggling for a bit as it kills all zombies that get within a certain range of you. It's pretty short, but it can help a lot.

PaP
The PaP is right by the quick revive and 300 kills/Electric Cherry teddy. It's in the food stand, in the upper glass shelves, it appears after round 10 and shooting it paps the gun you're holding.

This is the only surefire way to PaP that I know currently, but when I was shooting zombies once my gun randomly PaPed, so it might be possible to do so in this manner.

Tips
For early rounds, don't bother with QR, it's way too expensive and if you die before getting the other perks you are almost always better off restarting. I would recommend on knifing for the 1st and second rounds. Dogs are 1 knife forever, so if you have one on you all by itself feel free to just knife. Then try to do headshots only for the 3rd and 4th rounds.You want those headshots b/c deadshot is a necessity on this map. During the fourth round you should've hopefully gotten enough points to try the box once or twice, there's almost no weapon at this point that is generally bad, so just use it to get as many points.

Then once you have enough for jug and the 1750 door open it. You don't want to do that before because that makes the zombie spawns a bit more difficult, and if you're in trouble then you can open the door and somewhat safely back away taking potshots for once (will kill you 90% of the time after this, you gotta be really careful with space and zombies spawning behind you in this map). After you get Jug feel free to go into the next room past that 2000 points door (don't forget the gnome).

Then save up for the next door and a machinegun wall weapon (if your box rolls weren't all that lucky), after you have around 3900 then open that barrier and get your weapon. Now it is your choice to either save up for speed now or buying the 3500 door (i've found buying speed is a much better way, but I can understand wanting to get to the slightly easier training spot).

After you get Speed Cola and the rest of the map open, just train where you like to train and save up money to get Double Tap, Deadshot and QR in that order. After this save up for mule and by this point it's probably round 12 or so, if you want to feel free to PaP any machine gun you have. The pistols PaPed are terrible, the snipers and semi-autos don't need it and the machine guns all benefit greatly from it. Now if there is another way to PaP that I didn't notice please let me know, b/c then there's a lot more freedom in what you want to PaP.

Things I've Noticed
When shooting the zombies sometimes your weapon can turn into a ppsh-41, which seems cool until you realize that it's recoil and damage are♥♥♥♥♥♥ Takes ♥♥♥♥ing forever to kill zombies even with mainly headshots, honestly this feature is a real pain in the♥♥♥♥♥

The wall weapons as a whole are awesome. Except the Luger, it's just lame. Any of the sniper wall weapons will one hit headshot fairly late (from strongest to weakest it is the, springfield, kar, m-n). Don't bother getting the springfield as that scope takes so ♥♥♥♥♥♥♥ long to appear that it will almost always definitely kill you.

The m1-garand is fairly decent, but honestly both the gewer and the carbine are much better if only b/c their fire rate, mag size and actually being able to reload whenever.

The Bar is actually amazing, like holy♥♥♥♥♥♥it tears zombies apart, though it's ammo count leaves far too much to be desired. Honestly I like PaPing that or the M3 Grease Gun (M3, gets an insane ammo size, while the Bar just gets more awesome and a good ammo size).

That's all I got for right now, lemme know if any of this was helpful, and any other secrets you've discovered.