As for the printer:
http://uk.asus.com/products/communic...er-support.htm
That's the list of compatible printers from asus. You should also check out >Reported Compatible Hardware< in this forum.
I thing using two printers one on USB and one on LPT will not work... i think i have been reading some place that the USB port will overrun the LPT but i don't now if this is correct
Then about the modem.... many have reported that they can only use the WAN port for a short while before it "dies". I also had this problem, this is solved by using the customized firmware. (i don't know if you can fix it without) and forcing the WAN port to be 10 or 100 Mbit. (You might be able to set your modem to be 10 or 100 Mbit or do as other have done placing a 10 Mbit hub between the modem and router)
I hope this will help some and perhaps someone else has something more to add or correct