Keep in mind that Otos are sensitive to tank conditions. It has been known to have some die off for no reason. I've experienced that myself and I keep my tanks well maintained (weekly 20-30% water changes/cleaning, test water every mid week of cleaning, no chemicals used around tanks, no fish harassment of fish, etc.). At $7 a pop by you, they would be an expensive investment.
Regarding the hood, do you know what brand your tank maybe? I'm assuming that it might be Oceanic Systems, since it's a 53 gallon tank. They're logo should be on the tank so you can tell. They would sell hoods for their tanks. Otherwise, if you're unsure, you can go to a glass company and get 2 pieces of glass cut. You can also get the hinge and little handle for it at some aquarium sites. There's a little plastic piece that you can buy at cut out room for tubes, wires, etc. which can be purchased at any LFS.
Some LFSs carry the Eheim (pronounced EEHYM) in their shop, otherwise, you can order them online. If you have the money, I would get the model with the built in heater in the filter. This helps eliminate having a heater in the tank, which makes viewing inside the tank even a little better since all you would have inside is the filter intake and outlet, and the wire for the thermometer. The models with the built in heaters are the 2126 and 2128. It's always recommended to go above the size of your tank when choosing filters. I use a 2128 (designed for 180 gallons) on my 55 gallon tank. The current is not too strong, even for my Angelfish, who supposedely don't like strong current. I even added 2 powerheards to increase the flow.
Good luck on your tank. If this is your first tank, don't forget to cycle.

It takes at least 3 weeks to cycle a tank properly.