Not sure. Check around, lots of people are renting bikes.

I would go to Austin Sports Bike Shop on S. Lamar; better, lighter bikes, some of their rentals you may take into the Greenbelt. They have hourly and 24hr. For lower profile there are plenty around the lake and Zilker Park, even the City of Austin have bike sharing stations at all the right places that charge you as you use it. If going on summer time be prepare for the heat from 10am to 8pm, the worst is 12-6pm.

I know the rental place by Barton Springs is cash only, but Texas Rowing Center accepts debit cards. It's located on N. Side of River near austin High School

We used the free parking on South Pleasant Valley Rd. As you go toward South Lakeshore Blvd. or left from S. Lakeshore Blvd. and on your left.

Yes there is parking all along Lakeshore Dr which gives you immediate access to the trail.

The veloway is a dedicated path just for that: Attraction_Review-g30196-d6157435-Reviews-The_Veloway-Austin_Texas.html Only bikers, rollerskaters, and rollerbladers allowed. It's around 3 miles and paved.

The trail is NOT skateable. It is crushed granite. The trail has loops of approximately 2.9, 3.1, 4.6. 6.9 and 10.1 miles. Of course you can do "out and back" which many people do. The "zero" marker is at South 1st and Riverside and increases going west and then across the lake under Loop 1.