Regarding the car seats, during my last pregnancy I heard it was 20 minutes at a time, no more than 2 hours in a 24 hour period in a car seat that didn't allow them to lie flat... until they were able to hold their head up and sit up (supported.) It's an extra argument against the car seats that fit in the travel systems because of the length of time the baby can end up in the seat.
Practically, I reckoned that the occasional longer stretch was okay, especially as they got older. Just to get DS home from hospital was a 30 minute drive on its own.
I'm only 5 foot and the travel system seats dragged on the ground for me, so I got a lie flat pushchair-pram and a group 0+ car seat (newborn to 4 years/18kg) and lifted DS out into a cuddle hold. He'd just settle back to sleep happily, so I personally found the argument about the travel system seats not disturbing a sleeping baby were invalid for us.
We've just moved DS up to a group 1 car seat so that he doesn't feel usurped from lots of things when baby is born. We thought about a group 1-2-3 but couldn't get an Isofix one that fitted our car.
My feelings on this:
Travel system group 0 seat:
Can be taken out of the car while baby still asleep - could be useful, but if your baby settles back easily, isn't really that handy.
Can be taken out of the car and used for a safe place to keep baby when visiting a non-baby house - can be pretty useful.
Temptation to leave baby in for ages - not so good.
Very heavy and unwieldy - not so good especially if you have a c-section, and just gets heavier with baby.
Doesn't last that long - lots of my first antenatal group peers had to upgrade their car seats ages ago, DS still fits in ours, we've just chosen to upgrade him.
Most of them have Isofix and can be seatbelted in too, thus they fit a large range of cars, so very practical for getting in others' cars, and they're easier to swap between cars than the bigger seats.
You can strap baby in in the house, then quickly slot seat into its base, rather than faffing around outside when it's raining.
You can end up limiting yourself to the travel system selection which fits the car seat selection.
Group 0+ seat:
Stays in car all the time, don't have to worry about getting the fit correct after the nice person in the store puts it in for you.
Lasts a lot longer than the smaller ones.
You might have a wider choice of prams if you don't plan on buying more than one.
You're not tempted to leave them in the seat too long.
Can be really big and bulky and impair the driver's view out of the side window if placed on the left.
Older babies/toddlers have more scope for bracing themselves between seat and door frame when they don't want to get in when still rear facing.
Can be rear facing for much longer (a lot of people go forward facing when they upgrade the group 0 ones) - and there are arguments to suggest that rear facing is a lot safer in a crash.
Can be hard to get Isofix ones.
But we've just moved DS to a forward facing group 1 Isofix seat and it's SUCH an improvement that I can't argue for the 0+ that strongly.
It all depends on what you think your lifestyle is going to be, and that's a little hard to tell till you're living it.
Do consider your car - especially if you are changing car ready for the new family - our Renault Scenic has odd shaped seats so very few car seats fit well. It does have Isofix, but that doesn't help always. But we picked it because we only found 2 cars I could get behind the wheel while 20 weeks pregnant, with space to spare for expanding bump AND still be able to get the clutch down to change gear - and out of the two, we liked the way the boot was straight in with no lip, making getting a pushchair in and out at my height much much easier. The fact the seats come totally out too is great for transporting big things like the slide we just bought DS.
There are lots of carseats out there, but only a couple of manufacturers have "fit finders" on their websites. They corner the market, being very large manufacturers and add to that the fact that it's very convenient being able to sit on your sofa eating jaffa cakes with your feet up and the laptop just beyond your bump and click on what car you have and find out which seats will fit it, especially in a "hard to fit" car. If you're considering car buying, it's also worth looking up your shortlist and seeing if you get lots of fits (implying other brand seats are more likely to fit too) or few. Links: Britax and Maxi-Cosi
Talking of jaffa cakes, anyone want one before I scoff the lot?
(And on a further car seat note, I found the Easy View Back Seat Mirror really good for keeping an eye on DS while he was rear facing, and also the Babysnuggle or similar was good for keeping baby warm and cosy in winter in both car seat and pushchair and much easier than fighting reluctant legs into a pramsuit.)