1) Installer and resolution.
You are correct that it should only affect the application, Please ignore the resolution/installer "issue". This may still be an issue with the application and resolution.
"Can you confirm whether you are able to open the launcher after installation?"
No, because I am not sure of the nomenclature and the results I should expect. But when I run the shortcut labeled with a big "A", I get access to several pages with links to setup, wiki, forum, plus a big green button labeled "PLAY".
"- Is it in game client when you're trying to click "Enter World", or does it occur at another stage?"
My big problem is before the "World" (which I did enter twice, but can no longer access). Right now, when I press the play button, I am placed in a full page purple valley, with purple mountains (I call it "purple mountain majesty, or "PMM" for short"), PMM also features swirling orange clouds. Once there, I cannot find any exit and no key combination I have tried does anything. The only way out is to crash my system and reboot.