No. Overthrow v1.4 rebuilt saving and loading on top of Arma Reforger's own persistence system, replacing the Enfusion Persistence Framework. Saves made before v1.4 will not load, and there is no converter.
If you are not ready to start fresh, pin 1.3.34 in your config.json and update when you are.
In Single player just restart the scenario and choose "New Game".
To restart your campaign in ARMA Reforger Server:
OVT inside My Documents\My Games\Arma Reforger\profile\.save\. This is the default location of the "profile" folder. This location may vary if you specify a specific profile folder. Do not delete the settings folder next to it.If you played before v1.4, there may also be an old Overthrow folder in profile\.db. It is no longer used and can be deleted.
If you are using a game-server hosting provider you should contact their support if you cannot locate your "profile" folder. If you are using a hosting provider and deleting the save files does not reset the campaign, it is becuse they are caching them and you need to recreate the entire server again or contact them and tell them to not cache your files.
Overthrow saves your progress automatically every 10 minutes and when exiting the scenario or shutting down your server. In addition to this, officers can manually save the game.
As of v1.4 the save confirmation is honest — if a manual save fails, you are told. Previously it always reported success.
It just hasnt been written yet
First, you should determine if the issue happens with a base game scenario and not just with hosting Overthrow (including while not using extra mods). If you have issues related to client connections, etc. you should checkout the official ArmA Discord or forums for help instead of the Overthrow Discord.
If the issue is specific to the Overthrow scenario, then the Overthrow Discord would be the appropriate place under the #reforger-support channel.
Restocking happens on its own, once per in-game day at 7am, and no restart is needed. The same pass tops up town shops and gun dealers.
Before v1.4 only the gun dealer's own stocked goods (weed and similar) came back this way, and weapons and ammo needed a restart. As of v1.4 the dealer's weapons and ammo are topped up on that same daily pass. What a dealer rolled when the campaign started is restocked, never re-rolled, so a dealer that never carried a given heavy weapon will not start carrying one.
See Gun Dealer and Shops.
See Dedicated Server Setup and Overthrow Config
Only on a dedicated server currently. See Overthrow Config
In single player you should automatically be an officer. On dedicated server you need to login as admin by typing #login <password> into the chat box. Once an officer you can assign others as officers in the Resistance screen. You can permanently make yourself and others officer without logging in as admin using the Overthrow Config
Most mods that add weapons/vehicles/clothes/items will work with Overthrow. Those items will be available in shops/gun dealers as long as they are configured correctly and added to the Entity Catalog for a faction that is configured for Overthrow (ie US/USSR or RHS factions if you are using the RHS Compatibility mod). Note that gun dealers will not sell weapons from the Occupying Faction, and you cannot procure vehicles from the Occupying Faction at bases. Non-lethal items from the occupying faction will be available in stores. Unarmed vehicles may require further configuration to show up in civilian vehicle stores.
For a list of mods that have been confirmed as compatible with Overthrow, check the #reforger-compatible section of the Discord.