If you activate the ability multiple times during the same turn, Vectis Silencers will gain multiple instances of deathtouch; however, multiple instances of deathtouch are redundant. A creature dealt damage by a source with deathtouch is destroyed as a state-based action the next time they are checked, so a single regeneration effect will save it regardless of how many instances of deathtouch the source had at the time damage was dealt.

The only difference between a colored artifact and a colorless artifact is, obviously, its color. Unlike most artifacts, a colored artifact requires colored mana to cast. Also unlike most artifacts, a colored artifact has a color in all zones. It will interact with cards that care about color. Other than that, a colored artifact behaves just like any other artifact. It will interact as normal with any card that cares about artifacts, such as Shatter or Arcbound Ravager.