It is not advisable to have babies, ESPECIALLY high risk, medically fragile babies, in carseats except as necessary for travelling. Even normal newborns tend to decompensate (reduced oxygenation) in even correctly installed car seats. So if the baby you are adopting needs that much equipment, you're going to need to keep them out of the carseat as much as possible. A regular stroller that has a full recline is a better option, but the best option for a medically fragile baby is a good quality baby carrier that puts the baby upright on your chest (in a Kangaroo Care type position) any time they're not actually in the car.
So I wouldn't buy the car seat based on the travel system options, because you really shouldn't be using the travel system as such anyway.
My preference for short term jaunts (i.e. loading the baby in the carseat in the house so you spend the minimum time in the rain, for example) is something like the Flying Falcon car seat strap. But the idea of schlepping a carseat, stroller, AND all of the equipment a medically fragile baby needs? Sounds less than ideal.
It may be that the least "schleppy" option is to have a convertible (not an infant) seat, put the baby in a mei tai or wrap (whatever works best with the tubes/wires), and sling the monitors over a shoulder backpack or messenger bag style. This will maximize physical contact (very important for medically fragile babies) and minimize the amount of equipment you're dealing with. Having a special needs kid myself, the less total stuff I had to deal with, the better. At one point I was dealing with a low-tone baby, a senile mother in law with mobility issues and a dog on a leash, and a stroller would have made that all utterly impossible. As it was, I put her in a carrier, the dog on a leash, and still had two hands free to deal with everything else.
If the baby is special needs enough, you will HAVE to have a special carseat, as he may not tolerate the positioning of a standard carseat. Most monitors come with a bag with a strap. Oxygen tanks vary in size, but if they're larger, they can be wheeled, and if they're smaller, they come in a bag with a strap.
Feeding tube placement may affect your ability to wear the baby in a sling, but if you can find an experienced babywearing educator, they should be able to help you find something that works for that specific child.
I am not worried about the car seats till we know more. (thinking about the Coccoro if he doesn't need a car bed)
