Ok, I'll do my best here....

) How far out did you start training for your IM?

Well I had a good solid base from marathoning, so I only really started the hard stuff in January for my April IM. I really wouldn't start the long stuff too early. Your body can only handle that kind of abuse for so long. And you don't want to peak too early. I'd say 12-16 weeks of hardcore build is enough.
That is a steady ramp up in mileage of all 3 disciplines. BTW- my longest workouts were a 100 mi ride/ 8 mi run brick, or an 80 mi ride/ 13 mi run brick. For stand alone long runs I never ran longer than 15 miles, which is much different that marathon training.
And I did prolly 4 full distance swims in training. A lot of people do more than that, but I'm a crappy swimmer so I figured that I was wasting my time. More time swimming laps does not equal better form, sooo....
But anyway I did do a TON of 80-100 mi rides always with at least 3 mi run off the bike.

2) Did you get rest days in your training plan? Was it possible to get in the volume that you needed and get rest days?

YES!!! You have to take at least ONE day to rest up- mentally and physically. And yes, I was still able to get in my volume. But I did two workouts a day during the week. One in the morning, one in the evening. Usually about 1.5 hours in the morning and 1 hour in the evening. Even if that mean't spinning on the trainer while I watched t.v. for an hour.

3) Did you have a regular day job (aka: Basically 7-5 with getting ready, etc.)?
In 2006 for my first one, no. But my husband does work out of town during the week, so I was functioning as a single mom.
For my second one yes. But I had a very flexible schedule, so I was able to come in late on Tues and Thurs so I could get my 2 hour ride or swim in. So I really only worked about 32-34 hours a week. And yes, I was still functioning as a single parent. So it was tough.

So as you can see it is possible. I think it all depends on where you want to be performance wise. Do you want a sub 14 hour IM? Then you will have to put in a lot more time ( IMO of course). But for me I just want to enjoy the day and finish in an upright position with a smile on my face.