New to bass fishing and bass boats

I recently purchased my first bass boat, a 2011 Nitro Z7. I am looking to upgrade my electronics. I am not going to spend a ton of money. I am considering the Garmin Echomap 73 sv. My question pertains to transducers. I have been told that transom mount transducer are not fro me. Mine will be through the hull. When I look at what comes in the box, it is either a transom mount or trolling motor mount. I am assuming that I will need to purchase a through the hull transducer. There is a lot to know about a bass boat for a newbie. I welcome any help with what I may need to look at when I make my purchase. Currently the original Lowrance Mark 5x is in the console. Thank you in advance for any input.

Any transducer will work in the bilge except for side scan. A skimmer or puck is fine in the bilge. Use plumbers putty or modeling clay to form a dike around the ducer and pour about 1/4" of epoxy in the dike. Put the ducer in the epoxy and hold in place with a sand bag or brick until the epoxy cures. Thirty minute epoxy will work fine. Be sure the location is a single layer of fiberglass,usually right in front of the drain plug and clean the area very well. Use a solvent like denatured alcohol or paint thinner to remove all oil or gunk.
If you want to test a location for a good reading before glueing down,you can put about an inch of water in the bilge,site the ducer and hold it down with a sandbag for testing. I would recommend testing it first.

Make sure to mix slowly, I've been told you don't want any air bubbles in the epoxy.

Not too close to drain plug or it could block the flow. Sometimes, bits of line that was cut off, or pieces of soft plastics can go (blow) into your floor drain and you want those things to be able to drain out for the most part.
As for the air bubbles in the epoxy...once you put epoxy down in the bowl (dike), then place the transducer in it, and give it a jiggle or two while pushing it into epoxy. This will help push any air bubbles out to the sides.
Best if conditions are over 70 degrees for mixing a 2 part, 30 minute epoxy, otherwise it will be too thick for air bubbles to float up and dissipate. Let epoxy sit / dry for 24 hours before you take boat out. Directions on epoxy will say it sets up in 8 hrs, but that is not fully cured, it needs 24 hrs.

If going with side scan/down scan keep your Lowrance mark 5 in console to read depth while traveling at speed (side scan units generally won't read very well at high speeds). Then add your preferred electronics to the side or above your console. Sounds like you are set on side scan with the Garmin (which is really nice to have), and if so, you will most likely need to mount your transducer off the back of the boat or flush underneath the step just in front of motor foot. A side scan transducer will not work thru hull. Also consider other brands. Lowrance offers the ability to link console and bow mounts while Garmin is supposedly very simple to use. Be sure to check mapping capabilities, specifically that the Garmin unit has your lakes pre-loaded. If not, you will have additional expense purchasing mapping.

Bottom line is figure out what is important to you....side scan, down scan, or a combination of both.