400-500kg, by most accounts.
One of the risks, if the IRGC loses, is that they may poison the Iranian people as a parting shot before they take off to Russia.
Why would Russia or China want that group of trouble makers inside their country? Both are happy to use them against the US but not from inside their borders.
Sure- if they can get it - it’s under collapsed tunnels.
Everything you aid out (short of huge numbers like 20,000 bombs) was a risk BEFORE and why Trump had to do shat he did. This risk has been removed for years or decades even if we just walk away now - which we’re not doing.