Carseats

Take a look at these two websites:
NZ Child Restraints
Child Restraint Safety
...and the Car Seat Expert questions and answers on this site.

It's important to note that 6 months is far too early to front face baby - in fact it's safest to rear face them as long as possible.

A capsule (that you can lift in and out of the car, and snap onto wheels) can be really useful for the first few months. It's not absolutely necessary - you can get away with using a convertible car seat from birth - but I found having a capsule was great for being able to move him around without waking him. We probably wouldn't have gotten one at all but got one handed down from JJ's cousin and it was great. I'd say get a capsule if you plan on having more babies and can get the use out of it. Or investigate hiring one (eg from Plunket).

This thread and this thread both discuss whether you need to get a capsule.

As for convertible car seats, really depends on what's important to you, the range of costs and safety features and plushness is huge. But I'd personally recommend making sure they can rear face for longer

We had DD in a capsule until about a month ago, when she grew too long for it (her feet were kicking the back seat) and it was getting too heavy for me, (we have lots of stairs at home)

It was really easy to move DD around while in the capsule, she would stay asleep or sit in it while out at other people's houses or restaurants etc.

She is now in a S&S Royale which is huge but fits really snug in our car, doesn't move at all and is super comfy for her.

If DD falls asleep in her big seat now, she wakes when I take her out, and I have a smallish back door that is a PITA coz it doesn't stay open on its own, so putting her in and taking her out on a hill while dodging the tether strap is sometimes a bit difficult.

If you have the money, I would recommend buying one of each purely for convenience in the first few months Our lives were made 100 times easier with our capsule! Ooh, also I would try and get a capsule with a base - so much easier than seatbelting it in every time!

oh yes i second the base option too!!! loved it!!

i loved the capsule for my first. tried one with a base for my third and didnt like the base at all... capsules rear face and most carseats should as well.

I wouldn't bother with a capsule again. We had a convertible for Jack but ended up putting him in a booster with straps at around 2. Caprece was in the convertible but she has outgrown it and shes not even big for her age. Birth to four years my ass.