The 109 didn't get the DB 601 engine until 1938.
The early Bf 110 used the 700hp(roughly) Jumo 210s until some sort of DB engine became available, but still carried a considerable quantity of fuel, one source says 1270 liters.
The 109E carried about 400 liters of fuel, the Jumo powered versions carried 240-270 liters?
As far as the crew goes, you not only need the long range radio, you need space for the Navigator to spread out maps/charts.
The 110 was designed to hold three men in the cockpit, if needed, for certain roles. Which means the 109Z-early can't do some of the desired roles.