How to:

Automations (Enable for Sheet):
Sheet's Gear Icon Dropdown > 'Enabled Automations'
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.

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 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...

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.

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'.)

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