Hi Joan_2018,
Welcome to the wonderful world of Linux Mint and its excellent forum!
It would help to know more about your system setup. If you run "
inxi -Fxzd" and "
lsusb" from the console terminal prompt, highlight the results, copy and paste them back here, that should provide enough information.
Joan_2018 wrote: - iPhone contacts syncronization and backup (iTunes liking)
What exact model of iPhone do you have? There are various options and one of the easiest is to install a cloud provider's sync client software (free or paid for) from "pCloud", "mega.nz", etc... on all device (smartphones, tablets, and computers) and let it automatically sync with your computer and any devices you have the cloud sync client on including iPhones, iPads, all computers, etc...
You can try installing the Linux "libimobile" packages, see instructions in the link below. This is supposed to allow your Linux computer to communicate with your iOS devices.
Get iphone 7 Plus Photos Into Cinnamon 18.1 [SOLVED] - Linux Mint Forums
viewtopic.php?f=47&t=239521&hilit=iphone
There are a few file transfer apps like "Feem", Dukto, Nitroshare, etc.. where you install the apps in smartphones, tablets, computers, etc.. and exchange files that way.
Feem v4. Share Files Offline.
https://feem.io/
Joan_2018 wrote: - Garmin GPS updates from the app Garmin Connect, planning routes etc
Using Ubuntu to acquire and manage GPS data from Garmin eTrex - hselab.org
http://hselab.org/garmin-gps-ubuntu.html
USB Garmin on GNU/Linux - OpenStreetMap Wiki
https://wiki.openstreetmap.org/wiki/USB ... _GNU/Linux
ubuntu 18.04 garmin express - Google Search
https://www.google.com/search?q=ubuntu+ ... A3oECAoQBA
Joan_2018 wrote: - iMovie replacement (looking for OpenShot/Shotcut/Kdenlive etc)
Those are great video editors and there are more like Lightworks (lws) paid for version, DaVinci (if you have an nVidia video card), etc... There are also movie makers like "ffDiaporama", etc...
You can always install Virtualbox and a version of MS Windows in that along with any MS Windows software in that and run those while still in Linux Mint without dual-booting. Some MS Windows apps may run in Linux Wine like the Garmin Express?
Hope this helps ...