[Buildroot] Few question about Buildroot from a newbie

[jana1972 at centrum.cz]

Hi guys,
Can anyone answer these questions? As far as I know  buildroot is for varios embeded Linux 
systems.
Questions:

1. I have a Linux MIPS embeded device that I did not design so it uses some utilities and 
software  and behaves somehow. I would like to make it behave in a little different way. So 
my idea is to use the hardware but different software. Is it  possible?
if so, where should I start? Is there any tutorial?

2.When I build my software using buildroot, how can I upload it  to my embeded device?

Any help would be appreciated.

J.