Android App to send bluetooth commands

develop android application to send commands over a bluetooth interface.
Layout #1 - main action
- show list of paired bluetooth devices and allow to choose one.
Layout #2- 6 buttons and a slider
- send command through bluetooth serial to a selected device
When a button is pressed for longer than 100ms, send the following command repeatedly, until the button is released:
Button -> command
FWD -> LF<n>;RF<n> // n= 1.. 255 example n=128: "LF128;RF128"
BACK -> LB<n>;RB<n> // n= 1.. 255 example n=255: "LB128;RF128"
LEFT -> "LF<n>" // n= 1.. 255 example n=200: "LF200"
RIGHT -> "RF<n>" // n= 1.. 255 example n=100: "RF100"

"n" should be selectable by user using a slider on the same layout as the buttons.