complexity theory – A Query regarding Polynomial hierarchy collapse to a finite level

Assuming a hypothetical scenario that complexity class $PSPACE$ is shown to belong to complexity class $NP^{coNP}$ the Polynomial Hirerchy Collapses to a finite level.

Query 1: Which level the above complexity class belong to (level 2 or 3)?

Only a handful of important classes will survive this collapse. The only ones I can think of are:
$NC$, $P$, $MA$, $AM$, $NP$, $coNP$, $SZK$, $BPP$, $PH$, $P/Poly$, $NP/poly$

Query 2: Can someone enumerate some other important classes we missed?

Query 3: Now, given this unlikely result, what other problems still remain open in the complexity hierarchy above $P$ and below $EXP$ (other that the three below):

  1. $P$ vs $NP$
  2. $NP$ vs $coNP$
  3. $P$ vs $BPP$

Query 4: Does the above result also prove $AM=MA$?

In general this query is regarding the general landscape of Complexity Hierarchy in this unlikely scenario.