The data import solution can help!

You can check out https://impler.io/ it covers many of the features you mention and you can extend its functionality as well like converting first/last to fullname. Your problems related to edge cases, configuration, and support will be resolved automatically with it.

It's open source at https://github.com/implerhq/impler.io/

I'm a co-founder of it and if you create a feature request for something you want, I will happily cover it.