I'll share my experience w/ 4 kids 9-2yrs old. Just like running your household, establishing a system or routine is key to making things run smoothly. For equipment I use a cargo box & would never think of something else. At your height it may be a little challenge, but you'll likely step inside the door to reach up to load/unload. (Same w/ a ski rack). Keeping as much outside the car is always nice as you well know they fill the car with their 'must haves' to keep themselves entertained. Also I don't like the excess snow, mud, grime in the car to be mixing with the Cheerios and other things that are on the floor. You'll have bags, boots, coats, pants, helmets, etc in the back so that'll get filled quickly. Position of the box on the roof is also important so you're not reaching too far across or actually leaning back because it's too far to the side.
The other rule I have is you have to carry your own equipment. It's very tough for kids to carry skis. I created my own slings for them to carry their skis & poles. It is essentially 1" webbing cut to the length that would go across the chest so they can carry their skis on their backs. The 2 ends are sewn with D-rings to create loops that slip over the tips, then the tails (poles included if used). It cost ~$15 to make 4 of them and have worked great. I actually use them for storage as well by just hanging the skis on a hook via the strap. When I unload the skis from the cargo box, the loop is already in place, I just slip it over their head, put one arm through the loop, swing it to their back & off they go.
I found some small drawstring (cheap) backpacks that I use for their helmet, goggles, gloves & neck warmer. They always come out of the bag & go back into the bag. I don't have to do an equipment check. I just grab the bags & know all of those items are in there.
You'll figure it out, just be sure to be extra patient. They not only need to learn to ski, they need to learn 'how to go skiing' and all it entails to pack, travel, unpack, get to the lodge, get tickets/passes, walk around, etc. All the things we don't remember learning, but did along the way. Our first trip was a dry-run to the slopes. Didn't even ski. Wanted to get them used to routine. Get up, eat, get dressed, get in car, get out of car, get equipment on for carrying, go to lodge, etc. We're only 1hr from the slopes so it wasn't a huge time investment & spent the day playing in the 12" of snow that fell while we were there. I'd say after 3 trips, they were pretty much in the groove and now all I do is wake them up in the morning & they fall into the routine.
PS. I do this all solo, so I had to get very efficient. With 2 people it'd be much easier, but you still need a routine. If you want a pic of the slings I made, let me know & I'll take one to post for you.
#1 rule - Have fun. Not just the kids, but you as well. Remember this is simply sledding on your feet and should be just as much fun as that first day you took out your sled & slid down a hill. Don't get caught up in what your supposed to do, you're just taking the kids out to slide on some snow. What's the pressure in that?