You should take advantage of every tool and every study material you can get your hands on (or buy). That's the only way to keep up in this game.
- If you want to profit at SNG you definitly need to use a HUD (ie. with HoldemManager or PokerTracker).
- For managing multitabling TableNinja is very good.
- Study hypotetical scenarios, math and decision-making with SNGwiz.
- Review your sessions to find out mistakes and leaks.
Regarding opponents' ranges in MTSNGs:
Yes, ranges will be very maleable through the sng especially amongst regs. And so should yours.
But what you're talking about is not that easy to do. There's no magical stats. There are adequate stats that you should be paying attention but remember that opponents vary their play, so each hand deeper ITM is more situational dependent than just statistical or static range dependent.
The basic VPIP/PFR should always be there. But when analysing specific spots you may have to look at other stats (that should at least be in your hud popup) like ColdCalling (IP/OOP), 3B, LimpCall, LimpReRaise, etc.
But also very important is taking notes on opponents regarding their range. So taking notes on position, stack size, hand, and stage of the sng (eg. FT, bubble, etc). For instance you should note that "Villain Reg 123" is openshoving T8o with 7bb from UTG pre-bubble. Or that "Nit Reg 99" is capable of 3B shove QJs vs BTN min-steal with 4 players left, vs another reg.
With TableNinja I find it harder to keep up with the current session, the players, note taking and reads. So you can do it after each session.
Nowadays I prefer to play 10-12 tables without tableninja and make those kinds of notes while playing (I used to 24table cash games in 2011).
You should only increase table number after a lot of experience in decision-making, particularly only regarding to stats.