Arduino users advice needed

hi all.

in my growing white cat (http://www.le-chat-noir-numerique.fr), i decided to incorporate communication with arduino (thanks to VVVV to make me heard about it).

i received and arduino card and just establisehd good communiaction with it.
at the beginning i was thinking of following usages:
-using arduino as an IO and potentiometer box for my lighting board
-using arduino for motors and relays driving from my app

But in the last week, more and more i m reading around, more and more i m facing this question:
-how to define an open way for users to make what they want and I didn t think about ?

reading / writing data can user defined easely. I m using Bytes way to send in array IO and analogs.

but should i incorpore like a keyword scheme, that the user can define on his own and makes what he wants with arduino ?

is there a limitation for real time applicatiosn with the serial port on usb ?
I m using 9600 bauds rate/asking for data from arduino all 20of seconds, waiting a string for io of max 128 bytes, and of analog 64 bytes ( + header for keywords 3 BYTES)

well. really arduino is hudge and i m very aware that my definitions on how to use it is not enough.

Voilà ! i need advices and suggestions ;-)

I think catweasel did a good patch and an arduino file to use it as an input output object. Very easy to use.

http://vvvv.org/documentation/arduinofirmata

hi !
well firmata is included inside arduino and belongs sys ex family , if i well understood.
as whitecat community is NOT programmers but light designers or technicians, i was planning to make a more easier and softer protocol… well let s say affordable for shy / clever peoples… that want to create kind of macros, and i m planning to furnish a little libraries of tools and fucntion as arduino file also.
but thanks i will look more closely to firmata !

any other advice about usage you are doing of arduino ?
i m interrested in your experience and way to use it ;-)