Hello Victor,
I'm a semi-retired classical guitarist who has dabbled in home studio setups going back to the heyday of the Tascam 388 multi-track recorder. About 5 years ago I decided to take the home recording studio idea more seriously and now have a studio that meets my current needs. That said, there are many people on this forum with a GREAT DEAL MORE EXPERTISE than me! Hopefully they'll chime in shortly.
So.....I don't want your money but will help as much as I can.
The first step many here on the AGF will advise you to take is acoustically treating your recording space. Baffles, wall panels, ceiling panels, etc.. Here's a link to an old thread from this site that addresses the issue from a DIY perspective.
https://www.acousticguitarforum.com/...d.php?t=251366
The next critical step is probably choosing a microphone or microphones. In my experience condenser mikes are the way to go but there are so many choices you might want to start with a budget to expedite the search.
Your current nominees for audio interface and monitors looks good to me. I have a pair of Adam 7" monitors and they're ideal for my purposes. Having said that I rely as much on my headphones as I do on my monitors, especially during the recording phase. Like microphones the headphone selection is vast. So here again I decided on the budget first then choose the most highly rated set accessible at that price point where I live. Consequently I use Shure SRH 840 headphones most of the time.
Perhaps the best advise I can offer at this point is that you should at least consider upgrading to a more fully featured DAW than GarageBand sooner rather than later. While GB does offer some editing options it's very limited compared to many other recording softwares like Logic Pro X which is the most logical step up from GB. At the very least you'll want a DAW that lets you use sends for time based effects (delay, reverb, chorus etc.).
I'll follow along as this thread develops. Hope some of my comments are helpful.
Good luck!
Trevor