You should be able to go into 'resource' and look for .ttf files. Try replacing every one of them with the font you want. Depending on your hud, they may be located in a folder. If there are some that haven't changed, go to resource/clientscheme.res. (and any base files if there are any as well) Ctrl-F for CustomFontFiles. It should have the paths to all the fonts. Either replace all the font files it points to or change their paths to your font.

I'm having trouble getting preloading to work for some materials. I can preload and display "../vgui/pve/upgrade_owned" on pure 1 servers, but "pve/upgrade_owned" doesn't display correctly on pure 1 servers. I know I don't have the file paths wrong because "pve/upgrade_owned" will display my custom material on pure 0 servers. Basically: "pve/upgrade_owned" acts like it like it isn't preloaded but "../vgui/pve/upgrade_owned" will preload successfully. The upgrade station uses "pve/upgrade_owned" and won't let me change the path.

Those 2 paths are pointing to the same thing right? Am I crazy? I looked through the whole tf2_misc_dir and it doesn't have the pve folder anywhere else so it has to be in the vgui folder. Besides, it works correctly on pure 0 servers. And yet I can display both of those side by side in pure 1 servers and they show different things. (but the same on pure 0)

HudMatchStatus.res

The mvm upgrade panel is HudUpgradePanel.res However, the actual upgrades themselves (the part that shows the cost, how many points you have, and the + and - buttons are in UpgradeBuyPanel.res
scripts/hudlayout.res controls the area the the upgrade station covers. If you want to resize or move the whole menu you will need to edit it

I assume that you copied and pasted the scoreboard from another hud and didn't add all the fonts. Check what font it is using for those fields and make sure that you have that font installed.

I dont know for that one. I would suggest restoring back to the stock hud's version of the loadout screen and then slowly adding things back in until you find what is causing it. There won't be a file for it since the game generates the icons for war paints.