Yes, Alternate Art cards are more valuable than regular cards
Its arguable about whether its an upgrade to Paladin En-Vec because the lifelink would be better versus non R/X and B/X decks, but Id honestly rather skip both for Cube because of their inefficiency unless you really need Rakdos hosers
The opponents Leader may be attacked, or an opponents Character which is rested
A 2-mana 2/2 is still good in Limited, and it wouldnt be broken in Unlimited either
If you have the persist creature Murderous Redcap, you can kill it and bring it back with Celes over and over again to deal a loop of infinite damage to your opponents
Helga, Skittish SeerHelga, Skittish Seer also triggers even where you're casting Subtlety for its evoke cost, letting you recoup your investment and generate value in the process