The RC is intended to work on the mayor browsers: Chrome, Firefox, Safari, Edge. The graphical editor only works on desktop-like computers. All the mayor browsers have their little quirks and also some minor visual differences in how RC looks and works. I don't think I can really recommend one over the other. I tend to use Firefox myself, but the developers themselves and most others use Chrome.
I think I experienced the problem with the color picker as well, and will report it as a bug. I suspect is due to the browser auto-filling the field, which somehow "sabotages" the appearance of the picker, but will have to check! Thanks for reminding me of the issue :-)
The second issue sounds a bit more serious, if it occurs again, it may be useful to us to have the particular HTML so we can check if there is some conflict there. I don't think it is your browser, it may be your connection, but cannot rule out an issue with the RC itself, so we would be curious to know when it occurs! You can send any problem-causing HTML to firstname.lastname@example.org.