To force-Quit a single application: right click on the dock icon and select “quit” – or if it’s wedged, press the option key to toggle that to “force quit”
Multiple Windows of same application? command ` to toggle between them, or F10 to see them all.
Forward Delete: function + delete key
FTP application: I use Cyberduck (it’s free), works great and transmits data quickly (on my PCs I use WSFTP).
“Aim for the Useful”