I am neither a newbie nor an expert on Linux, I have been using Linux Mint for most part of my work and hobby for years, simply because I hated MS Win so much ! to be precise I am using LMDE the original Debian, not the commonly used Ubuntu clone, it is more difficult to handle and less support than Ubuntu.
Some said Linux is buggy and unpolished, yes it still is in some way, so that updates keep pushing in everyday, things improved a lot over the years. On the applications for example Libreoffice, the best MS Office replacement in the Linux word, still has problem with Excel files. Most of my problem with Excel file is the grid line, there are always broken grid lines when open the file on Excel after edited with Calc, this is no doubt a bug need to be fixed. On the other hand, MS Office will randomly crash and need reinstall, this may triggered by a corrupted file, or something Excel can't read, but you can't predict when this will happen. With Libreoffice, if it crashes at some point it will stay crashed at the same point until you fixed it, that's the difference between the two system ! may be MS Win is too smart has it's own mind to decide what to do, you can't tell what will come next !
Beside office document I also work with photos and graphics, I used GIMP for retouching, it may lack some features but more than enough for me. I also use Darktable as Lightroom alternative to handle RAW files, and Handbrake for DVD to MPEG conversion....etc., if you need to run your favorite MS Win apps on Linux you could use Wine, or the commercial CrossOver, even Virtualbox, there are many reviewer running Virtualbox on their PC/Mac for testing Linux.
Regarding dual booting Linux and MS Win I also have the same problem with my T440s, my workaround is disable secure boot and select boot partition on the BIOS instead of using the boot manager, that's the easiest way to do it !
Btw, my ThinkPad got a 16G SSD for windows hibernation and I did not use that, so I install Mint /root on it, and /home and /swap on the regular hard drive, this way I can boot up Linux super far without the need of a large and expensive SSD ! I also found that, I can install Linux Mint on a regular hard drive/SSD, and then boot it via USB with adapter, it will boot on other PC as well, that's how I make my Linux portable !