You're wrong. They tend to look at the maximum possible sentence for the offense in the jurisdiction, and a conviction is a conviction. .
Yes . that is true. Otherwise one convicted for illegal gambling
in one state can argue that he is not doing anything wrong because
another state allows such gambling.
On the way around, if you do something legal in one state, USCIS can
not say you are a bad person because the same thing would mean an
offense in another state. Of course some things are not crminal
but still reflect bad moral character like being a habitual drunkard,
legal prostitution in Neveda, etc
What can be tricky is if an offense happens in double jurisdiction
(locat estate and federal). Say if you steal something like a pensil
from a post office and you are only charged ,tried, and convicted by the state for petty
theft and federal court never bother to prosecute you, Let assume it is a petty theft by state law only punishbale
by less than 6 month but stealing federal property can carry up to 2 years by fedeal law
will USCIS measure what possible sentence the federal court would hand down?