There is a size limit of 24 inches for a computer monitor. That would be the only limitation (I have no idea what macs are limited to with monitors etc...... I still have ((and will hopefully remain so)) windows.)
I would suggest, however, that a small flat screen tv with a computer input or a computer monitor with YWR inputs. I got a computer monitor with just computer input, and it was annoying when I realized that I couldn't hook any type of game console to it.
There is nothing in regulations about type of printers. Although I would suggest the academy bookstore printers, as you can later white card ink for it at the bookstore. Just make sure its compatible with the mac.
There are also company printers, so in theory you don't really need a printer, but most of them have been OOC a lot. (out of commission)
As for sub-woofer, I have one myself. I don't think that there is a limit to the size, but use reason. Keep in mind, 4/c will not be allowed to have speakers or play anything out loud till they are granted the privilege to do so, which is usually a few weeks before the end of 4/c year. A good pair of headphones might be of more use until then.