The latest models of 200DX come pre-wired with a NEMA 6-50 240V plug and also come with an adapter for use on 120V, if you have the dual voltage option. That breaker setup is for two circuits. The 40 amp portion is for your stove and the 30 amp portion is for your dryer. You can use either to run your welder. It only needs 30 amps and you will find a few people here that use a dryer outlet as a temp setup, one guy even runs a 100 foot extension out to his garage. But that will need to be 10 gauge. You can adapt a four pin outlet to a three, just not the other way around. So it sounds like for now plugging in to your stove outlet might be the way to go. What kind of stove outlet do you have? It should be marked on it.