Steve,
Good choice on the transponder. You can't go wrong with that one. Even if Canada goes forward requiring diversity (or any other countries do) and you want to comply, you're just a software upgrade and antenna install away from compliance.
I've got a write-up here that may be more than you want to read, but it's got some tips in it.
https://www.myrv10.com/N104CD/upgrades/NGT9000/index.html
Off the top of my head, I can tell you that if you have an AHRS option with ARINC 429 output that you can feed into it, that's a nice addition. Here's why: For traffic to display in the proper orientation to you, while not moving, your transponder needs to know your heading. So, traffic does not display and you may get a "traffic unavailable" type message as you start and stop moving during taxi. I believe at around 7mph it will use your track and turn on. But, if you don't want this alert and you want traffic to display any time the system is ready, if you feed it the AHRS so it has heading, that will fix it.
Other than that, it's a straight forward install for the most part. Power, Ground, Altitude encoder input. There's a little module that you connect with 4 wires, that stores your config and licenses I believe, called the DCM module that you install. The RS422 output can be connected to RS232 systems in most cases, for a standard feed to your EFIS. Look at the manuals Aspen section in the appendix for how to wire that. The wifi module attaches with power/ground/TX/RX/Signal Ground. Interestingly, you can do some configuration via wifi once it's configured the first time. Plan to have a windows 10 laptop on hand though to run the config utility when you set up the transponder. For the most part, that is very intuitive as well. Them manual documents things well. Click through every screen and read the manual and you'll get it right most likely.
ABSOLUTELY install the audio output into your audio panel. It's awesome. I'd put it to an unswitched input if you can. It doesn't do much for annoying random callouts. Their traffic algorithm is fantastic.
You'll love the box. The weather and traffic display is more useful than you'd think, even though it's on a small transponder screen.
Oh, and when installing the config utility, make sure to follow the driver installation exactly as it's in the manual. It's easier to get things right the first time than to do it wrong and re-do it.
From a hardware perspective, there's just one thing I can offer for advice. When you assemble the wiring connectors on the back, and have them ready to attach to the back of the mounting tray, there are 6 screws that hold 2 angle brackets with slots to zip tie wires to. Those 6 screws seem to be weaker than some I've used. When you put them in the first time, it should go well, but if you have to remove them, they are easy to break. I'm not sure if it's because they have thread locker pre-installed, or what, but I broke one on each of my two installs. So when you go to put those on, be careful. Note from the install diagram that there are 2 jumper wires for chassis grounds that you install. Don't put the screws in those spots until you're ready to put the jumper wire on. That's the only hardware thing I ran into.
Hope that helps.