Golden Hammer 50%

I don't fully know how they work. Would be grateful for the following answers

1) If it fails, will number of hammer applied increase?
2) If hammers applied is increased, but no additional upgrade slots is given, can it be gotten back with a clean slate scroll?
3) If it fails, can I still apply 2 Vicious Hammers?

1)yes
2) no idea, i dont think so
3) No

I used 2 from an old event, both failed. it said i applied 2 hammers. I would not recommend using them for end game gear.

1)yes
2) no idea, i dont think so
3) No

I used 2 from an old event, both failed. it said i applied 2 hammers. I would not recommend using them for end game gear.

@Stereo; yes, if a item has been hammered once you can use an event 50% since you can hammer an item twice