Stardust Amplifier (S.A) states that when it gets a bonus for base attack, other allies gain a +1 attack.

1)I tried S.A with Gold Lace-shield (gives +2 attack until end of turn), and an ally 2/4...

I had Rampage ( Due to opponent's dimension ripper) in play with Crimson Vest. It is still not stacking with the extra 2 health.

Do look into it, thanks.

Crimson Vest ability says that for "each enemy killed, gain 2 health". I had an Evil ascension in play, and when 2 creatures were killed at
the same time, it does not give any cumulative stack of...