In your position, I'd find a low place (such as the first floor ceiling, or in the basement if possible) where the existing pipe is clear and cut it off square. Before doing so, get a flash light and mirror if needed and determine where the pipe is supported. With those cast pipes being as heavy and brittle as they are, it's important to keep keep them supported securely. When possible, I like to use a circular saw or 4 angle grinder (cut off wheel) to do the cutting. They cause less vibration than many alternatives. If you need to use a sawzall, use a fine toothed metal cutting blade. Consider fernco fittings or others of their type to join the new PVC to the existing cast. You can get them from Home Depot, Lowes, Ace, etc. If you use silicone to seal up the new fittings (shouldn't be needed) be sure that everything is darned good and dry first.
No you can not play a quick play spell card the turn you set it. Yes if you run into Mirror Force you can activate My Body as a Shield from your hand.