You may want to first consider your electrical situation. Do you have room in your panel to add circuits? Room for a double pole breaker? Are you comfortable adding circuits?
To install an element in the brew kettle you'll need to drill a 1.25" hole and use a 1" locknut. You can get them at Bargainfittings.com, among other places. You'll probably want to wire the back of the element inside a water resistant box and then to a box with an outlet and a switch controlling it. I personally like having a switch in each box. Be sure to use GFCI receptacles. 20 amp is needed for 2000 watts. To figure the amperage, just divide the watts by the voltage. So 2000 watts divided by 120v = 16.7. Hence a 20 amp box.
Wiring for 240 is more complex and requires a double pole breaker with two 120v lines. What turned me away from this is that I couldn't find the parts easily. I don't think they make 240v gfci receptacles so you have to buy a double pole gfci breaker. They were expensive and I would've had to go to an electrical supply place to find them.
Here's a good primer on electrical. Really helped me out.
Hard mounting in your kettle has advantages and disadvantages. You'll need more elements and you'll either need a dedicated 20 amp line for each or a system so you don't turn more than one on the same circuit on at a time. I find the 2000 watt elements to be what I need. 2 will heat up strike water fairly quickly. Sometimes I use a third. 2 will maintain a strong boil in 13 gallons. If you only have 5500 watt element, it may be too much for the boil. Then you have to look into one of the ways to dial it down.
I think the simplest solution is to use heat sticks. I used
this design Only brewed twice with them so far, but they perform great.
The third thing to consider is ventilation. You'll create quite a lot of moisture and want to have some plan to deal with it. I went with an exhaust fan venting out the window.
Here's my electric brewery. Maybe it'll give you some ideas.
Good luck. People here are unbelievably helpful and even just searching the forums often yields everything you need to know. Get her built!