Actually, mine has three screens! Tools, etc, on the left and layers, etc, on the right. They can be turned off though and, presumably, everything accessed from the menu bar at the top.
Yes, I have no problem saving a file as .xcf and have exported files as .jpg too. I find no problem with that
There are some things, though, that I found easy under Photoshop but struggle with in Gimp. For example, in PS I can draw a rectangle around an object and move it or isolate it for various functions, such as erasing. In Gimp, I've found out how to draw a rectangle (or ellipse) around an object, but am still not sure how to move it, for example. I'm sure it's just a matter of learning procedures (and 'reading the manual'!).
Looking at that list of plugins is impressive and reminds me of non-Windows software like Linux where various contributors have added, and continue to add, all sorts of probably very useful things, all of which appear to be free to use.
Yes, I'll persevere, and am presently trawling through the included help file bit by bit.