Hi,
I'll be thankful if you can advice me about a day trip to the lake Como.

I'll be staying some days in Milan this July. I want to spend one day around the lake.
I've been in Como city before, so this time I will to skip it. My main target is Bellagio and I'm thinking about doing some walk in the morning, having late lunch somewhere and spend the afternoon --until public transportation connections to Milan allows me-- in Bellagio.
I'll be travelling by public transportation, not by car.

According to a Lonely Planet guidebook, one way to do this could be Milan-Como by train, then Como-Bellagio by bus. But I've seen a comment somewhere about going by train to Varenna and ferry-crossing to Bellagio. Do you know which option is better?

And, do you know about a good / scenic / etc walk s-w around the lake of about 2 or 3 hours?

Am I missing something essential in this trip, that I could do instead the walk? For example, spend some time in a beach, weather permitting? (I've read that most of the lake beaches are not public and need to buy an entry.)

Thanks in advance!