. . . and I'm a little concerned about crossing over the streams. Is the water level very high relative to the rocks or logs used to cross them?
Terry, the only stream crossing of any real concern is the first one (going up) over the North Fork of Lone Pine Creek. It's a long crossing with a cascading drop-off about 5 feet to your left. Excellent rock hops are placed just right, so normally the biggest challenge is avoiding getting your feet wet. The next one of any significance is Lone Pine Creek at Outpost Camp, and it's relatively shallow and level.
Just be aware of the stream levels throughout the day as melt occurs. When you begin at 2:00 am or so, the North Fork should be running pretty low and not present any great difficulty - not a lot of snow melt going on at that time. Later in the day, however, as the snow above melts out in the temps and sun, it will very likely be raging and the hops could be well-covered. This is when it's just no damn fun - and you're tired, to boot.
The best move on your return - assuming daylight hours - is to stop at the John Muir Wilderness sign below Lone Pine Lake and take a sharp right - and follow the Old Trail back down to the Portal. This bypasses the North Fork crossing and actually cuts 15-20 minutes out of your return hike. The Old Trail is a bit rugged and steeper than the primary trail, but makes an excellent alternative to crossing flooded rock-hops when you're whipped, or have concerns about the balance/stability of others in the group. It comes out just above the wooden bridge at the Portal driveway loop.