vaughn,
"My main concern is not wasting a bunch of time on trying to figure out how things work...also I don't want to waste a bunch of money also."
Unfortunately I think the two factors are mutually exclusive. You'll need to have some idea on "how things work" or you will likely be wasting a bunch of money.
I'll send you some information via PM on using transit in Italy. It may help you avoid unnecessary charges.
I provided some Itinerary suggestions in my first reply, and hopefully some of those will work for you. I can't help with Air BnB suggestions as I never use them, but I'm sure the others here can offer some suggestions on that.
For planning sightseeing and the optimum location for accommodations, I would highly recommend having a look at the RS Italy or RS Paris guidebooks. If you have a Library in your community, they may have copies there. As most of your trip is in Italy, you may want to pack along a copy of the Italy book.
Your location appears to be reasonably close to Denver. Should you happen to be in the Denver area on Jan. 21, you may find it helpful to attend the next meeting of the RS travel group there. I'm sure the group there will be able to help you sort out some of the details for your trip. The information on meetings is in this thread.....
https://community.ricksteves.com/travel-forum/travel-meetings/denver-travel-group-meeting-dec-17