There's a lot of keybinds in SCUM that aren't always obvious to the player. Here's a list of some of them.
Auto-Walk: SHIFT + W
Toggle Weapons Light: SHIFT + E (works with handheld flashlight as well)
Switch Fire Mode: SHIFT + LMB (single fire, burst fire, etc)
Check Fire Mode: SHIFT + Hold RMB
Zoom In: ALT + RMB
Zoom Out: ALT + LMB
Scope HUD Brightness: ALT + Mousewheel UP/DOWN
Hold Breath: CTRL (hold)
Find Range/Wind, etc: CTRL (tap) - will take less time to find range as sniping skill goes up
Zero Range: SHIFT + Mousewheel UP/DOWN
Raise/Lower Crouch Height: CTRL + Mousewheel UP/DOWN - helpful when you need to make fine adjustments
Volume up/down: Page Up/Page Down
Switch Stations: L / K
Craft most recently crafted item while not in TAB menu: ALT + C (good for crafting large quantities of items like lockpicks/arrows)
SHIFT+Q to open your health tab.
Open tab menu: SHIFT+C (Recently, TAB seems to do the same while in a vehicle)
Note: You either have to be in single player mode, or be an admin on a multi-player server to use drone mode.
From the main menu:
CTRL+D to toggle drone mode
While in Drone Mode:
CTRL+H to toggle drone HUD.
Mousewheel to increase/decrease drone speed.