Croaker

I'm thinking of going to Italy for 2 weeks in August. This is my first solo/backpack trip and my first time to Europe. I want to keep it pretty loose as far as itinerary so that I can stay longer in one place if I like it and not be tied to a schedule. I want to see Rome, Venice, Amalfi and the Herculeneum. Here's my questions:

Do I fly in to Rome and stay there as my base, taking the trains to Venice and Amalfi/Herc?
Or should I fly into Venice then travel down and end in Rome?

I've never stayed in a hostel and have more than a few reservations about doing so. It's not that I'm anti-social. I just like my privacy, perfer my own bathroom/shower and would like a place to leave the bulk of my stuff safely while I go exploring. Besides, aren't there age restrictions for staying in hostels? I'll be 40 by August. Are there affordable 1 person rooms to be had in the hotels? I was thinking of staying at the convents. Anyone have any experience staying in them? How strict are the curfews? I'll be packing pretty light and can carry everything with me as I explore I guess; I'm just used to carrying only an atm card, some cash and my digital camera.

Should I get a Eurail pass before I go or is it better to buy a one way ticket when I'm ready to go to the next city?

I understand that Venice and Rome get a bit crowded in August. I was hoping to just book a room for my first few nights then find places to stay as I go along. Am I being foolish thinking this way?

When visiting the Herc I was hoping to stay in Amalfi a night or 2, see the Herculeneum in a day then go back to Rome. Is this possible?

Any suggestions on things to do and see along my route would be greatly appreciated.

Thanx. I'm looking forward to learning from you all. This place is very informative.