95% of your questions can simply be figured by just inspecting the hud element:
You can open vgui_drawtree, tick 'highlight selected' & pause game/demos to figure out exactly which element you need to target if you browse the tree of hud elements!

Clientscheme econ related colors names in BaseSettings, use showschemevisualizer clientscheme to figure out which color is which.

Disable floating health, position stuff, then enable floating health, the TargetDataName and TargetDataPanel move over when the health is in the ID.

• MainMenuOverride.res defines how your main menu looks
  
• GameMenu.res defines the actions/commands for the buttons in your main menu

You have to make sure the fonts and colors used in the main menu file are defined in your ClientScheme.res

NA rulesets I assume, with which whitelist?

The issue in the screenshot is because the imgur album page url was used instead of the direct link to the image (basically adding .png/.jpg). Internet Explorer will display 'missing/corrupt image' where chrome/firefox will just collapse the section instead.

@No1inPartiqlar use [url]-tags if you link to the album or actually use the direct image link between [img] tags for them to show up in your thread instead of only being visible when someone quotes the post.

I assume you mean bottom left, but you're looking for the following 'states' of labels/buttons _default, _armed, _selected for the normal look, when clicking and going over the button with your mouse.

Edit ItemSelection.res similar to your ClassLoadoutPanel.res (where you have to fix your model_tall and model_wide in modelpanel_kv for your skins to show up properly

LobbyPanel and LobbyContainerFrame are for the MvM co-op and the Competitive Lobby screen.

The pasted section is the hudfile, which is not responsible for the animation. This is in a scripts animation .txt file in the DamagedPlayer event which is targeting the DamageAccountValue(BG) elements.

You can use vgui_drawtree in your main menu with the Highlight Selected ticked to find out which is what element in your main menu, it's just under a different section in the tree.

There is a way by toggling certain graphic related settings:

mat_antialias 0 // Change this value between 0 and 1 to see main menu changes without restarting

Rename your custom folder temporarily and validate your TF2 files through the Properties in Steam and see if it still happens?

Does the following in console fix the issue when it occurs?

record random; stop

Use tf_scoreboard_ping_as_text 1 if you want numbers back (or go into advanced options and fiddle with your settings)

If you actually want to remove it from the scoreboard try:

scores {
	ping_width "0" // or -1
}

Setting medal_width to 0 will hide the stamps if those have to be removed.

You made the panel with the classmodel full screen, but did not move the class 'into' the screen. Mess with the 'origin_z' values and reloadscheme to see the changes.

Are you sure it's not closer to 0.82?

The default font for the overhead playernames is SpecatorVerySmall

Instead you could change/add the following to 'HudSpectatorExtras' in your hudlayout.res:

HudSpectatorExtras
{
	"player_name_font"	"Default"
}

Also the right place for this question would have been here.

you can manually disable all reskins, but weapon skins and certain action items are enabled by default because they don't affect the game unless certain convars are set or map types are loaded.

So this is the whitelist (takes care of every stock reskin (botkiller/festive/skins)
How are you enforcing this whitelist? TFTrue?

HudMedicCharge?
Wouldn't be too hard to figure out by looking at this list and guessing what names of files might represent ingame.