There is a picture from Canairradio dot ca of a Toronto ACC console and I just assumed that 24 hours in advance worth of FPS are set up at the console.
No, they're always coming in. Here's a pic of what an inactive board looks like (I don't have a pic of an active one):
See the tube sort of thing just below the NY OCN divider? That's how they come to you, and they just come flying out sort of whenever -- usually 20-30 mins before the actual aircraft gets to your sector, to give you enough time to get them in holders, put them on the board and scan for conflicts. You will get multiple copies of the same strip, as well, if the aircraft is passing over multiple fixes within your specialty. Keep in mind that in the low sectors, a lot of the traffic is GA too, or VFR flight following, so a lot of the flights are somewhat impromptu, requiring the controllers to grab a blank strip and write one up on the fly. It's the job of the data controller to take the strips from the tube, put them in holders, and slot them into the correct spots depending on the fixes. He also coordinates the fix ETAs with other sectors, and discards the strips once the aircraft has been handed off or lands. The radar room is actually a relatively noisy place and about 97% of that noise is the CLACK-CLACK-CLACK of plastic strip holders hitting other plastic strip holders as they are jostled around. It's a bit archaic, but the majority of conflicts are still caught this way, and in many cases the radar guys can fix them well before they even show up on the screen.
I've always wondered who on earth is manning the freq that split away. I've often heard contollers mention "Sorry, I was on another frequency, say again please? " So if a center is busy, there are more controllers. Can one controller man 2 split frequencies even after saying wishing 'good day' after a hand off?
All the rostering is done depending on traffic levels. For instance, the East Low specialty has a max of 3 controlling positions: two radar sectors (Simcoe and East Radar; there is no Peterborough sector but Simcoe sector has a secondary transmitter, with its own frequency, that is based in Peterborough) and a databoard position which sits between the two and works with both sectors. During a typical day shift you have 5 guys scheduled, so at any given time three will be working the positions and two will be on break. It's an equal split, so you do an hour in Simcoe, 45-minute break, an hour in East Radar, break, an hour working the databoard, break, rinse, repeat. Sometimes on Saturdays or Sundays the two radar positions are combined. And then during mids, one guy will work both radar sectors and his own board (despite this, it is still VERY slow, and you can easily work 2-3 hrs. without a break -- in fact you have to because they only roster 2 guys to work the entire specialty during a midnight shift, so often one guy will work while the other just hangs out for a couple hours at a time, then they switch). The RsiT displays that we have can be adjusted so that any console can work any sector, or combination of sectors, in the entire facility. In fact each controller has his own login name, and once he signs in with that name the display alters to match his specific preferences regarding centering, zoom, colors, what's displayed vs. what isn't, and so on. NavCan doesn't pay as much as the FAA, but our equipment is like an IMAX movie versus their black-and-white TV (at least as regards the facilities that are still using ARTS).
When a controller says "I was on another frequency" he usually means an intercom call with another sector or facility. This is all the stuff you don't hear on liveatc.net. It greatly depends on the sector but in some areas at YYZ, I would say there is probably at least one "landline" call for every 2-3 calls on the actual frequency. All our interfacility handoffs -- to Montreal, Boston, Cleveland, Winnipeg -- are done via the landline, and there are lots of pointouts, apreqs, and other stuff, both within YYZ sectors and outside the facility, to coordinate. When this is going on you're still technically on frequency, but it's kind of like trying to listen to someone talk to you on the phone in one ear while somebody's standing there yelling into your other ear; you know that a pilot has called but you often don't know who it was or what he wanted.
Regarding splitting two frequencies and switching pilots from one to the other (which I think is your last question)? Yes, it happens, usually due to range issues. You might have a pilot who's losing you on the PIA transmitter so you switch him to a different frequency on a transmitter that's closer to where he is. Technically you're supposed to say something like "change to my frequency on xxx.xx" that lets him know it's still going to be you, but I guess technically you could phrase it the same way as any other handoff ("contact Toronto Centre on xxx.xx") and then just surprise him when he still hears your voice on the other end.
Hope this helps to answer your questions.