I have basically replaced my laptop with my iPad Pro. I didn’t replace my server or media editing machines with an iPad. Google docs is more than sufficient for my needs.
I didn’t take pictures and it wasn’t an exciting adventure. It did take a day of tinkering to get full video acceleration but that’s because I installed Mojave and the tools aren’t finished for that yet. My video encoding time went from 8 hours per hour of video at 1080p to 20 minutes.
I don't think it particularly matters if you update the os before or after you install the apps. You should definitely do a clean install, then have it migrate from the time machine backup, which is an option migration assistant will give you.