If a card specifically states that it moves Commanders from the battlefield to the Command Zone, anything that's been mutated onto your Commander moves along with it, then falls off - and will probably be stuck there, since there's no way to cast non-commander creatures from the Command Zone
The four Commander decks have been reprinted twice, so the supply of them is not as restricted as it initially appeared, but you'll still struggle to find them in shops now
DreamUp can help you create models even when you dont have a clear idea in mind or need inspiration
With seven power, RMS Titanic makes enough Treasure tokens for you to re-cast it during your second main phase with the commander tax, and you'll still have one extra Treasure for later
Neheb, Dreadhorde Champion can help you generate potentially tons of mana
That we can only activate as a sorcery is a small downside for being able to reliably return dead creatures to the battlefield