Thank you! I've upgraded my Kindle Paperwhite 1st gen to 5.4.4 and I can confirm that everything seems to run great on it

(Kindle Menu too)
Regarding the app "kindcalc"... Kindle Menu does already embed a calculator app (Galculator). If you want to edit that icon to replace it with a Kindcalc shortcut instead, you could give a glance to the section "Guide: How to add your custom app launcher to Kindle Menu:" in the first post of this thread