By electric do you mean SMAW (shielded metal arc welding), ie consumable electrode with a flux coating? If so I know you can weld stainless steel with SMAW, I'm not so sure about aluminum (I think you might be able to, it would just be difficult and messy)
MIG welding is alot harder for me than TIG. Other people will say the opposite.
When TIG welding I usually set the flow to 20 CFH (Cubic Feet per Hour).
Starting a MIG welder is easy, you pull the trigger, wire comes out of the gun, touches the metal, creates an arc, and starts depositing wire into the weld bead.
You could braze-weld steel/stainless to aluminum, but not weld. Welding aluminum is REALLY easy if you have a machine that will do AC and HF (High frequency).
Welding steel to Stainless steel is fine, you just need to use 309 filler rod.