Even if many platforms and apps cover most of the features you mention, only a few cover them all.
I've been using Movavi for over a year, and it's been great for my video projects. It's really easy to use and has all the features you mentioned, like clipping parts of your runs and comparing them. Plus, it's compatible with Windows 7. You should check out this link for more details and features: Top 9 Final Cut Pro Alternatives for Windows in 2023.
I’ve worked with GoPro footage a few times, usually chopping up longer runs and putting side-by-sides together for comparing laps. The trickiest part was always matching up the clips so they're perfectly in sync for side-by-side viewing. I’ve found that lowering the resolution to 1280 for sharing makes a huge difference in upload time, and the video still looks decent for web viewing. For reducing size even more, experimenting with the H265 codec helped, but not all players support it easily, which did trip me up once or twice. If you start working with MKV files, you might want to look into mkv merge for combining different clips or sources. Makes merging multiple video files pretty straightforward without a big learning curve.