If the tractor starts and runs, you did it just fine! Almost any small amount of air in the system and your tractor will die. That screw (plug), was that at the top of the filter? If so, thats the air bleed. Simply loosen it, pump the crap out of that dinky little hand pump until you see fuel come out, close the valve. These tractors are actually really simple to bleed. If you're referring to the bottom plug, the one on the bottom of the filter, you should only need to loosen it for fuel to come out. Hopefully its only fuel and not water, but if water comes out, this is what that plug is for. If no fuel comes out....
We had older equipment on the farm growing up. No working fuel gauges. The best way to tell how much fuel you had was to open the cap and look in! I ran those tractors out of fuel a few times growing up. The first time it happened, grandpa did the reprime while I watched. The second time, he supervised me. Crack the lines as they enter the injectors one at a time, turn the engine over several times until you see fuel come out. Tighten it and go to the next. Keep doing this utnil the tractor starts. When you run the battery dead, better have jumper cables and the pickup nearby. If you burn up the starter...
Good times indeed. But
@Cycledude Sounds like you did everything correctly. Good job!!