Hi.
Looks like you have spotted a bug - fields that should not have been allowing decimal points have been. Oops.
I suspect there may be more of those still lurking, since I tend not to put decimal values in.
Regarding the button usage, unfortunately that is out of the control of the application. It is up to the phone to assign which button does what.
Thanks for your feedback.
If you spot any other bugs, or have any ideas how the applications could be improved, please let me know.
Carl