Steve, there's no need to take an escorted tour to the Cinque Terre, and I wouldn't recommend doing so. You'll be able to move 'round and about the dense crowds - much of that bulk comprised of tour groups - more nimbly on your own. All it takes is a bit of reading up and more questions here, should you have them. As Mike said above, this question is asked a lot so a search of the forums will provide lots of info! I just wouldn't probably reference any threads older than a couple of years.
To get you started, here's one from earlier this year where I've provided links to the park's website (the Cinque Terre is a national park), some trail info, and some helpful Trenitalia train info for getting into/out of the region as quickly as possible via the two trains noted.
https://community.ricksteves.com/travel-forum/italy/best-cinque-terre-day-trip-tours-from-florence
Ferry schedules are not yet up for 2020 but should vary little from 2019's
https://www.apathtolunch.com/2014/06/complete-cinque-terre-portovenere-la.html
This is the actual website for the ferries:
https://www.navigazionegolfodeipoeti.it/en/
Last year's schedule, mid April to mid October:
https://www.navigazionegolfodeipoeti.it/en/timetable-valid-from-04202019-to-10132019/
Prices, other than a day pass, fluctuate according to distance traveled and time of day; explore by clicking on departure ports listed on the left of this page:
https://www.navigazionegolfodeipoeti.it/en/rates/
You generally don't want to use the boats as your primary means of transport but take one, say from Riomaggiore to Monterosso or Vernazza and work your way back to La Spezia, stopping at Corniglia and/or Manarola, by train or by trail where possible (note certain route closures).