Cycling UK Forum

Hello friends. New to this forum. Planning on the Salzburg to Grado bike route in mid August with my nephew. Have a bunch of questions and will really really appreciate detailed answered. Plan is to fly into Venice. Ride the train to Salzburg. Do the route in 4-6 days (not with a group, just the 2 of us). Then spend a day or so in Grado before returning to Venice to fly out. Questions:

1. Can we do this route on our own or do we have to go with a commercial group? (we prefer doing it on our own).
2. We have road bikes (thin tires). I have heard there are stretches or gravel. Will a road bike be safe or do we HAVE to have gravel tires or a hybrid bike?
3. Are there towns along the way where we can rent a hotel room and stay the night without planning ahead?
4. What's the weather like in Mid August?
5. Should we bring tents with us in case we can't find a hotel to stay in? Is it safe to camp out randomly?
6. I noted someone said lights are needed as there is a tunneled segment. Any other important supplies?
7. The segment where we have to take a train, how do we get tickets for the train - on the spot or do we need to book ahead of time?

I have looked online for several weeks now to get information about this ride and this forum seems to be my best bet. I will appreciate any feedback.