I have the iPad Pro 10.5 and just got a regular MacBook with the m3 processor and 256GB of storage within the last month to replace my older Surface Pro. I should probably mention that I also have a pretty powerful custom built desktop computer; but, it's not used much unless I need the processing and RAM power.
I'll start by saying that I love my iPad Pro - it's extremely portable and it can do 90% of the things I want to do. If I'm trying to get work done, Word, Excel, OneNote and PowerPoint work really well on the iPad. If I want to read a book, Apple's eBook app and the Kindle app are awesome. Need to search the web - no problem, Safari and Chrome work just as well as the desktop browsers would. Want something fun to do - the games are pretty awesome, and the Netflix app just work (chances are that your favorite streaming service has an app). Based on the apps that you mentioned, the iPad might work for you - the Office apps don't look much different than the computer versions do, and as long as your aren't creating super complex functions or macros, it'll be fine. The Quicken app might take some getting used to though - chances are that it's a simpler version than the desktop app (I don't know, not something that I use).
So if I love my iPad so much, why did I get a MacBook as well? ...so the problem with my Surface was the super annoying flap on the back; which is almost the same problem with an iPad and the keyboard that Apple makes for it. It's just not meant to be used on the lap, or tight places like the tiny table on planes. Being back in grad school I wanted something with a keyboard that I could use on my lap and that was also backlit. I could have purchased a Surface Book, or some other portable laptop; but, also having an iPhone and iPad made me want to get the MacBook so that I could take advantage of iMessages and FaceTime on the Mac. Now I can leave my phone in the car or upstairs, and simply answer a call or message on the MacBook or iPad, whichever device I have with me.
I find that I usually use the MacBook more at home though, it's not my go to system - that's still the iPad. The Apple pencil makes it awesome to take notes on OneNote, and the iPad also has a 4G/LTE plan, so I don't have to worry about always finding a hotspot, or killing my phones battery by using it as a hotspot.
If you really want to keep using your keyboard/monitor, then I'd get a MacBook, or maybe an iMac. You can use a Bluetooth keyboard with an iPad; but, chances are that you might have to purchase a model that's designed for an iPad. You can also plug the iPad to a monitor; but, some apps don't support external monitors and trying to display an iPad unto a monitor, or even using AirPlay to an Apple TV can be a bit of a hassle. Even with a MacBook, you will probably have to buy certain dongles to get your keyboard/monitor to work.
As for the file situation - highly suggest that you use OneDrive, it works great with the iPad and MacBook. This means you will have to spend about $70-$100 on a yearly subscription; but, it includes tons of storage (enough for most of us) and Office - save all the files on you computer in OneDrive. The other upside to this is that if your computer finally crashes, it's not a problem, all your files are in the cloud. I suppose you also get iCloud instead; but, it does not include Office, you will have to open your documents use Apple's office alternatives - Pages, Keynote, and Numbers (or Google solution; but, same challenge as getting iCloud).
Maybe go hangout at a Best Buy or Apple store for a bit, and see which setup you prefer - worse comes to worse, you can always exchange them within a certain period. I'd advice getting AppleCare on whatever you decide to get. Have fun shopping and best of luck on whatever you choose to get!!