Rvanbeers, I did something very similar to what you are planning. First off, like was mentioned, the back/lower bolt on each head will need to be loosened and then held up as you go to lift the head off of the block. I was able to get my hand on the backside of the head and use my thumb to hold the bolt up. But, the rubber band trick is good too.
As for the exhaust header bolts, just tear into it. If you break off the studs, you break them. In my case, I broke off 3 of them and all 3 broke off at where the nut was. So, removing the rest of the stud was nothing more than taking a pair of vice grips, grabbing what was left of the stud and spinning them out.
Like was said, PB Blaster will be your friend.
As for gotchas, the only one I had was on the passenger side, there is a metal coolant line that runs there and if you are not careful as you are lifting the intake, you can bend this tube (don't ask how I know). The good thing is the tube is only like a $15 part as I recall.
When reassembling the motor, if you read the book on how to do the timing, it will confuse the living snot out of you. This is what I found. You will need the #1 cylinder (front, passenger cylinder) at TDC (top dead center). This should be found by turning the crankshaft so the key is in the 12 o'clock position. From there, assemble the motor. When installing the timing chains, look at the chains. You should see a bunch of light colored (steel) colored links and then 2 links that are dark in color (may be the opposite depending on what chains you have). If you look at the gears that you had to put on the crankshaft, you will see a dot at the 6 o'clock position. IF you look at the camshaft gears, you will see a raised oval (looks like a tic tac). You want to put 1 colored link on the dot and the other colored link on the "tic tac". You may need to rotate the cam gear a little bit to get this alignment. Also note that you need to make sure that you keep the left chain on the left side of the motor and the right chain on the right side of the motor (make a note as to which is which as you are dismantling the engine, personally I would recommend getting a bunch of 1 gallon zip lock baggies to put all of the similar parts together, ie, all your intake bolts, all your front cover bolts, your timing chain/gear/tensioner/rails from the passenger side, etc). Once you get the colored links aligned, the timing will be good and you won't have to worry about any damage on start up.
As for the head, based on what you are talking about doing, it is highly advisable to do both heads. Yes, it is going to cost you a little more, but you would hate to be doing this again in the near future because one side of the motor was pulling more power than the other, leading to it failing. You are looking at about an extra $60 and an hour or so of your time. Cheap insurance if you ask me.
The repair to the head will more than likely involve having a machine shop grind out the valve guide and put in a sleeve. This is making an assumption that you don't find something else as you are tearing down (may find a nice dent in the top of the one piston from where the valve struck the piston).
As for the rocker coming off, I know why. If you have the valve cover off, the rocker is being pressed upwards by a combination of the valve spring (attemping to close the valve) and the tensioner (the round cylinder at the other end of the rocker that is sticking out of the head). In your case, what happened is the cam pushed the valve down, the valve stuck down as the lobe on the cam released its downward push. This allowed the rocker to not be forced into the cam any more. The spinning cam then pushes the rocker out from underneath it and allowing it to float around inside the valve cover. There are 2 dents (1 on each end of the rocker as I recall) that keep the rocker from sliding out since they are pressed on to the valve and the tensioner (hence why when the valve stuck, the rocker could move).
Take a look at the heads. make sure that you have the upgraded heads that fixed the plug thread issue. The bad heads have 3 threads for the spark plug. The new heads have like 6. If you have the heads off, now is the time to Timesert all the plug holes to prevent future issues (hence why I pulled off my heads as I Timeserted all 8 holes). Granted, while I had my heads off, I did a minor port/polish job to get me a little more power too.
If you need to know any more, let me know. Like was mentioned, take it slow, note where things come from and it will all go back together with no issues. Thinking about it, there was 1 other thing that I fought with for awhile and that was removing the harmonic balancer. It seemed all the pullers I was getting were just a titch too small and would not allow me to bolt it up. So, make sure you have a good size puller. If you have questions about installing the tensioners, let me know. A paper clip is your friend with those. Just don't forget to pull the paper clip out before buttoning up the engine.
