It will be a 305 or a 350 fuel enjection engine ( TBI )
look under the hood. there should be a label that tells what kind.
16 bolts on the trany oil pan is a 700r and 12 bolts on pan is a 400r
5w30
R134a
Should be a 700R4 Trans.
4L60-E
Obd ii
4L60E.
rocket fuel
15 to 18mpg
If the Blazer is gasoline powered the antifreeze can be any kind that is for sale for gasoline powered vehicles.
You should have this verified but the freon is probably HFC134.