B4R Question 48 keys keypad

I want to build 48 keys alphanumeric keypad including some special function keys i.e 'print' and 'total'..etc
my questions are(please accept my apology for asking many questions)

can I implement this with rkeypad, is there a max number of rows and cols?
how can I assign non printable ascii in initialize statement to key?
is it also possible to use analog pins in rkeypad library?

thanks