Use cockpit by Red Hat. It gives you a GUI to make networking changes*, and will check if the connection still works before making the change. If the connection doesn't work (like the ip addresses changed), it will undo the change and then warn you. You can then either force the change through or leave it be.
Netplan is an abstraction layer, so it can go over systemd-networkd, NetworkManager, or iproute. I suppose it's better though, because it can be used with multiple backends.
No. Netplan uses it's own yaml format, which people would have to learn and use. I don't want to do that, I would rather just configure my existing networkmanager setup, rather than learning another abstraction layer over what is already an abstraction layer.
I understand that cockpit (and similar type tools) are "the whole kitchen sink" of utilities, and it may seem like they come with more than you may need. But that doesn't change the fact that they get the job done, and in some usecases, are better than dedicated tools.