itch.io

If that isn't working then it's probably bugged

Once you shoot the flamethrower it should reload automatically If you have ammo

Updates are kinda frequent. you can get information about upcoming versions via discord I believe.

Download the game and extract the file from the zip. If you can't I would recommend using either winrar or 7zip. 

After that just open the file and run the .exe

On June 1st 1.9 was released for patreon subscribers

By subscribing to the patreon for $15 you could get the most recent release (1.9) 

Itch io players get the version before which would be 1.8 and it's out now for free

No.

Frequent updates though

Just download the new version and launch it and your progress will be there, after you've launched the new version you can go ahead and delete the old one.

Your save is storaged in a file in appdata, so you don't have to worry.

Be sure to launch the new version before deleting your old version though cause that might make you lose your progress.