Glogal brush - users asked to find a quick way to use the same brush in Paint and Eraser tools, and we added "Erase" blending mode in Paint tool (also available in Quick Menu). Paint Tool with Erase blending mode = Eraser.
Brush Preview (cursor) - it will be added in next major update.
Layer Mask - if you want to move/transform/elastify layer together with masks just select them all in Layers popover.
Color bar - option you mentioned is already there, go to Preferences > Finger Function When Pencil Is Connected, and choose Eyedropper.
App closing - document is autosaved when minimizing.
About the global brush, is nice you added the erase blending mode, but sadly it takes longer to access it than setting up the eraser tool to match your drawing brush... even if its in the quick menu (quick menu breaks my workflow). Sadly i had to move to Mediabang app, the workflow there is nearly flawless with the floating shortcuts bar, is super easy to change from drawing to erasing with the same tool, flip horizontally can be set there too... dunno, its super convenient, and the app is free, altho i purchased the no ads option to support them. Hope someday you reconsider addind a floating OPTIONAL bar where we can place shortcuts, i dont say your solution is bad, but for my 9,7 ipad there is no room to easy tap with 4 fingers while drawing.
Also, the captcha is super annoying, it takes a ton of tries and is super slow for some reason :S