What's that piece you added to the locking spigot, and how did you attach it?

Everyone has pretty much covered everything. The only thing that I would add is that you will need a way to accurately measure your volumes. I would suggest making a dip stick. Without knowing your volumes you can't accurately measure/calculate your efficiency.

I marked my pots so I don't have to use a dip stick. There is no risk of using the wrong stick with the wrong kettle and I cant loose the stick or my wife can't use it as kindling for a bonfire.

I sat my kettles on a level surface, opened the spigot and filled them until water started coming out. Then I closed the spigot. This is the dead space. The liquid that's there that you can't reach or use so it does not count so much. Then I measured out and poured in one gallon of water. Then I used a punch (or a nail) and hammer to make a dent at the liquid level. Then add and mark the next gallon and continue going until the pot is marked. Since things can get messy and my attention span is shot before I can count seven dots I find it helpful to make the level marks in some type of pattern.

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I would suggest not changing too many things at once. It'll only lead to frustration. Make a few extract brews with your new setup dialing in boil off rate and whatnot. Do you have a chiller? Maybe get a chiller and also focus on temp controlled fermentation. Fermentation is where it's at no matter AG or extract. If you can't nail down precise fermentation temps, you'll make average beer at best no matter what you do hot side.

Pudge, between the duck hunting fishing and boating I'm at my limit of hobbies here on the home front! I'd love to have a fermentation chamber but don't think I'd be to popular here at home if I took up even more room in the garage! As far as the wort chiller, it's in the works hopefully I'll have time to make it this week.