Brian, just did both Whitney and Dana last week. Here goes:
Dana has several large snowfields between 11K' and 12K'. We used micro-spikes for two that were considerable uphill slogs, but they're doable without the spikes. There were quite a number of smaller snowfields between 20' and 60' in length that were just nuisances.
Whitney - several snow crossings, but the only one of consequence is the one just before Trail Crest and directly above the snow chute that is used to access the mountain in winter conditions. As of last week this chute is still completely filled with snow. You'll find that all the other snow crossings are trenched - i.e., deeply trod footpaths that give you a sense of stability. The snow crossing above the chute I'm referring to was not trenched, and gave a number of folks the willies. It's 1600 feet down the chute if you slip. We saw several people turn back at this point and call it a day. Spikes will help here, but really only when it's crusty earlier in the morning or later in the afternoon. You will want trekking poles, as well. My wife and 11 YO daughter crossed this chute, but were very nervous doing so. Use extreme caution and small steps, and you should be OK. Get across it on the return before it loses the sun and turns icy.
Water from the pond at Trail Camp is fine for filtering. Trail Camp has seen relatively few campers so far this year, and the steady snowmelt stream from the chute above is keeping it flushed pretty well. We filtered there both last year and this year. Also, it's really a challenge to get down the ledges to Consultation Lake for water - I've camped there three nights within the past year and never even tried. All our camp cooking water came from a snowmelt stream directly across the main trail from Consultation Lake.
The last place to obtain water is around the 23rd switchback between Trail Camp and Trail Crest. It's source is a spring and is flowing strongly during the daytime hours, flooding a number of switchbacks in the area, but it can dry up in the evening. Go ahead and tank up at Trail Camp with 3-4 liters per person, and you won't need to worry about the switchback stream.
The cables are a non-issue. Wide, dry path all the way through. The switchback immediately prior to the first cable post is snowy, and may require a 10-foot uphill scramble to re-access the trail, but it's not a challenge. It may be melted out by the time you're there.
Hope the beta helps. Have a great hike!