Getting Around Italian Lakes

Very good ferry service up, down, and across the lake. Here is the website where you can download the ferry schedules, although the summer schedule is not out yet. http://www.navigazionelaghi.it/eng/c_orari.asp
There is likely to be even more frequent service then.

Train will get you up the east side of the lake north of Varenna.

Yup, ferry between towns, varenna is a fine choice as a home base because of train accesibility, there are also small pleasure boats that will just take you out on a loop to enjoy the shoreline

For a fun day, ferry from Varenna to Menaggio, bus to Lugano, Switzerland, train to Como, and hydrofoil back to Varenna !

It was just enough time to wander and drink cappuccinos in each location !

Sounds lovely, thank you for the suggestions! My Airbnb host recommended I rent a car but I'm not sure I want to drive around on my own. May not be cost effective since I'm alone and who knows how parking is in these lake cities.. Train and ferries seem good enough!

The ferry will take you all over the lake ! Go to Bellagio, too.

How costly was the transportation from Varenna/Lugano/Como and back to Varenna?

I don't remember ! But look at rome2rio.com and the prices do appear.

You could research the ferry and train schedule, however, for their pricing.

Does anyone out there know those websites ?

I've found Rome2Rio's prices to be all over the place and do not trust them. You can usually drill down to a link to the appropriate bus/boat company's website and find more reliable information there. If that doesn't work, try Googling "Bus X to Y", etc., and follow the likeliest looking links.

http://www.navigazionelaghi.it/eng/c_crociere.asp is the boat site.