Yes

She mentions them twice. 

It happened during this flash.

Dave’s eyes can be seen here.

You can see Dirk’s eyes in this flash.

On this page. 

Ancestors are a concept in troll society that are responsible for contributing a greater proportion of their descendant’s genes than the incestuous slurry from which troll eggs are produced. They share their descendant’s signs, horn shape, and blood color. High bloods tend to put more stock in their ancestor’s existence while low bloods don’t usually care about them too much. Because of the reproduction process of trolls, ancestors are usually long dead before their descendant hatches. However, they may still be alive if they’re a long lived caste.  

Rainbow Drinkers are essentially the Alternian equivalent of Twilight vampires. They can withstand sunlight and radiate light. They can also run very fast. Kanaya and Porrim’s conversation in the Openbound flash games confirms that the condition is directly related to jade blood. Kanaya theorized that jade bloods developed the condition after being in the dark birthing caverns for so long while Rose theorized that they developed the abilities in order to scare away predators from wigglers. 

Aranea states here that blue bloods only occasionally have mind control powers. Vriska states here that yellow bloods sometimes have those abilities like Sollux and that telekinesis is common to rust bloods.  

The ancestors are the same Beforan trolls just under different conditions. This is mainly seen through the Condesce’s behavior since her and Meenah are very similar.

Yes, by using your Sacrificial Slab.