Yip, your on the right track, I usually split the ball joint first, takes the tension off the arm that way, big socket to undo those two big bolt heads you mention, (they are threaded into a plate on the other side that goes across the two bolts, so you wont need anything to hold the inside.
You will probably find some shims between either one, or both of the bolts, and the main arm pin, and the chassis, just make sure you take a note of where they were so you can put it back that way when you put the arm back in, they affect the wheel alignment/Castor/camber etc.
If you undo the nut on the steel pipe from master cylinder to the top of the hose, it means less to take out to get the arm out.
you will need to undo the bracket on the underside of the arm that the brake hose routes through as well to get the arm completely clear.

sounds like I have done this before, only twice, honest
If you strike any snags, just give me a shout.
I will try to get some pics to add to this post, so others that need it can follow it, but not tonight, I've been up since 3 am, and its close to time for some sleep.