XCore Exchange

i have my own board and have used all the 1-bit ports so i would like to use a couple free 4 bit ports so that my stdio stuff like printf() and getc() still work. from what i can tell, you can alter the .XN file to use the ports you want but how does that apply to multibit ports? does output (e.g. printf) drive every bit on a 4-bit port? does input (e.g. getc) require every input pin to have matching values? finally, is the stdio protocol used UART? if not, what is it?

thanks.