I use the Device for the majority of my code editing and second your request to search the help file on the device.
It is very time consuming using the device help whilst trying to write new code for a function that you are unfamiliar with. For this reason I tend to use the PDF help file created by juergon that can be found here http://www.b4x.com/forum/showthread.php?t=52 and I use an application switcher to flick between the code editor and PDF file.