Artificer If I cast Arcane Weapon and set it to deal Acid or Poison damage, does it benefit from the Alchemical Mastery?

Is the Artificer meant to be able to take a second attack with magic crossbow without the Crossbow Expert feat?

What to give the Artificer at 7th level? It’s a bit of a dead level at the moment

Artificer: Is it safe to assume proficiency with light crossbow & the heavy was a typo?