The real best way to get the necessary textures, models and sounds are by downloading Insurgency's Dedicated Server.
It is also heavily recommended for many reasons, first being that they use the original texture sizes unlike this pack.

For those who don't have INS2, are too lazy to get it back, don't know how to extract it and yaddablahdurhur, here is a pack.

This pack contains materials, models and sounds for all the INS2 weapons included in this SWEPs pack.
Materials have been modified, they all had their size reduced by x2 so their quality is lower but at least so is the size (As well as performance, your videocard may need to use less VRAM).
Models have been directly extracted, no modifications.
Sounds have been directly extracted, no modifications (For now).

Note that I said "weapons", hands are not included. You're forced to use CSS hands, rig 8.

Here is the download link; http.s:/mega.nz/#!HplgyQrK!-WhK3qNiUjcWJOB2Th0-pE9du0410N_R1kF99QEvTHU (REMOVE HTTPS FROM THE START)

How to install it? Extract the .rar pack then put the "Insurgency M&M Pack" into your "garrysmod/addons" folder.

All credits go to NWI.

Side-note; I am doing this as a "collective favour". I don't want anybody whining even a bit about it, I just wouldn't even care. If there IS a problem, you can tell me.
As I said, I am not being paid for this, KnifeKitty didn't tell me to do it and, truly, I did (nearly) everybody a favour, so you like it or not, I ABSOLUTELY don't care. Wanted the original textures? Too bad.

Regarding DOI, I have no plans to do it until the game is finished (not barely-finished, but finished).