I dont know the answers to most of your questions.. but I can tell you I got the wolf 36 inch nov 2008 and I LOVE IT.... I know I need 6 inch clearance for air under it. THe appliance store that you purchase it from should be able to guide you on the install.

This link should be helpful.
Lisa

Here is a link that might be useful: The Induction Site

Check the appliance forum for more opinions.

Most of the induction cooktops have their inductors (guts) made by just a couple of manufacturers. The differences are in the housings, electronics and features.

When you choose your model, go to the manufacturer's website and you'll be able to find installation instructions to answer your questions about the depth. It's highly variable because of the fan and ventilation requirements. Generally, you either need cabinet space underneath or an air channel behind the cabinet.

The different features, besides the ventilation space required include the sizes of the elements, fan noise, how much power each has and which ones share power, power boost, plus whether there are individual controls for each element or if you have to select the element before you adjust it, programmable elements with countdown timers (some have them and some don't), and number of power levels available.

The power levels number is confusing. A lot of the units number them from 1-9 and have half steps in between. So they really have 17 power levels even though they only list 9. Some have a "program" so that you can switch between 9 and 17 power levels. And some have special, additional high and simmer levels.

If you check theinductionsite.com you'll see a good comparison of the models available. It's not 100% accurate and up to date, however, so if you see a model you like, go to the manufacturer's website and read through all the documentation to see for sure what's what.

If you just want a flat recommendation, when I thought I was going to buy a 30" unit, I decided on Miele. It's quiet, isn't a cabinet hog, has 17 (programmable) power levels, individual controls and I think it has true timers (the individual element countdown to shut off timers). Plus Miele's excellent reputation for customer service.

You've gotten good advice so far. The only thing to add is that induction is hard wired in - no plug ins and typically you will need room for a junction box in your cabinet and 40 or 50 amp service. The appliance specs will tell you this. We installed ourselves (that is we dropped it into the cutout) and the electrician finished the hookup.

If you buy local I would think the store would hook it up for you or if you have to order it in the manufacturer could recommend an installer if your builder is not comfortable with it.

I went with the LG 30" induction cooktop based on the burner configuration and the bridge element. We are very happy with it. It did have a failure out of the box with one burner but it LG got it fixed in less than a week (Thanksgiving week no less!) even though I had purchased it out of state, not locally. We have not any problems since and we use is several times a day.

As for the cabinet working - someone is selling your builder these cabinets and I think could help you once you have a unit picked out. My unit fit in the cabinet without any adjustments but my KD said that reordering a drawer so the cooktop fits is not unusual at all.