If you'd have had to heat the manifold to get the plugs out, you should heat teh manifold, not the plug. The manifold will expand slightly and make it easier. Just like removing exhaust mainfold studs.
Don't put petcocks in the block drains. Use plugs. The petcocks can plug up easily with silt.sand/rust and leave water in the engine.
'06 X2 MCX
"I understand why some people may not want to do this the way I have recommended but I can't understand the death grip some people have on a toilet plunger with a hose fitting." -JimN