How to:

Automations (Enable for Sheet):
Sheet's Gear Icon Dropdown > 'Enabled Automations'
-OR-
Sheet's tab dropdown > 'Enable automations'.

Automations (Disable for Sheet):
If automations have been enabled for a sheet, they can be disabled via Overview dropdown > Disable Automations.

Attacking: (Automations must be enabled.)

Auto-Eject Toggle:
Touch the warrior data header select the desired option.

Adjust Heat

Manual Marking/Unmarking

Ammo: Dump:
Touch the bin and select 'Dump'. Ammo will begin dumping after selecting 'Next Turn' and complete dumping after selecting 'Next Turn' again.

Ammo: Change bin for weapon:
Touch the bin and select "Use". If there are multiple weapons that could be linked, select the weapon in the critical hit table.

Critical Hit:
Add and remove by touching the critical slot and selecting Crit/Fix.

Customize/Construct Units:
Flechs Sheets does not support unit customization/construction. However, you can import custom unit files (.mtf) from MegaMek Lab or Solaris SkunkWerks, so long as Flechs Sheets supports the unit's equipment and configuration.

Fall:
Touch the Overview header and select fall to force a fall.

Download MTF for unit:
Select 'Download MTF' from Sheet Name or Tab dropdown.

Offline Use:
Once loaded, the URL sheets.flechs.net automatically supports offline access, just go to the URL while offline (go ahead and give it a try, I'll wait!) — though the unit list and network features will be unavailable.
Want a launchable App-Icon?
Safari (iOS): Browser 'Share' Button > Add to HomeScreen.
Chrome (Desktop/Mobile) : An install button should exist on the options screen. Tap to create a launchable shortcut in your Chrome apps folder (desktop) or homescreen (mobile).
Firefox (Desktop/Mobile) : Similar to iOS... I think...

Jam/Unjam:
Touch the component in the critical hit table and select Jam/Unjam.

Movement Change:
Touch the move mode in the overview panel and select the hexes moved. To set to stationary, tap the currently highlighted move mode.

Name Pilot:
Touch the Pilot panel header and select 'rename pilot'.

Link to specific unit:
Select 'Link to Design' from Sheet Name or Tab dropdown.

Prone:
Touch the Overview header and select prone to set unit prone.

Rename Sheet Tab: A sheet's tab will display the pilot name instead of the unit designation if the pilot is named. (See 'Name Pilot'.)

Shutdown:
Touch Overview panel header or the Sinks header and select shutdown.