You don't "need" a pass or IC card. The question is if it is worth it or not. The 72 hour pass is 1500 yen - that is 500 yen a day, which is very easy to make worthwhile if you are going around the city. The 48 hour pass is also possible, but harder to justify. The 1 day pass is nearly impossible to make worth it.
Using a Pasmo or Suica card is very convenient, but you save extremely little. The Pasmo card has no refund fee if you want to get your money back at the end of your trip, but the Suica card does, and would likely eat up any savings you get off of your fares anyway.
Yes I think so. 3days pass cost 1500 yen(=$14)
Minimum charge of metro is 170(cash) or 165(ic card). So if you take 9 times or more, it’s worth it