A number of years ago I built a 120v EBIAB system with two 2000w elements when I was in college. I brewed for a while then took a break from brewing for about two years. A couple days ago I decided to break out the gear and brew two 5gal batches of a Peanut Butter Chocolate Milk Stout. Needless...
I was in the same boat when i built my eBIAB system. Reading though a lot of posts on this site and theelectricbrewery.com, I found enough info to get my rig built. I use two 20a 120v circuits to run two 2000w elements in my kettle. The link below is my build thread. Take a look at my wiring...
Nice build!
One of these days I'm going to buy a nitro setup. I want to buy a small chest freezer and add a collar like you did first though. I turned an old fridge into my keezer and can only fit two kegs in there.
A simple fix to that problem is a $5 carboy handle.
I've been using carboys that were once my grandpas (they're around 45ish years old) and have yet to seen one break. I hope they never do, but if your careful with them they can last a long time.
Bevaragefactory.com
Kegworks.com
MidwestSupplies.com
Bargainfittings.com
Northernbrewer.com
You can find most (if not all) of what you need on these websites.
DME can just be poured in, but make sure you turn off the elements before you add any LME. If you do decide to use LME make sure you clean your elements very well after every brew.
I use two 2000w elements and its very effective for 5-6 gallon batches. It doesn't take much more work to add the second circuit. You probably won't be able to have a good boil with only one 2000w element.