Which One

For tyre pressures talk to your tyre retailer or simply look at the tyre plackard mounted somewhere on the vehicle, maybe in the glove box or on the body in one of the door frames. It is probably listed in the owners manual too.

As for which compressor? You will get as many answers as there are brands. If you buy something with a name brand on it then I am sure it will do the job. I have an ARB and I am happy with that. You may be able to get something that will do the job for less money. I still carry a very old $20 plug in to the cig lighter job I bought from Target years ago. Still works and is a useful back up. It will do one tyre in the time the ARB does three. Pretty slow but a 25% time saving, (Or is it 33%?) if ever I am in that much of a hurry.

You are thinking right to get a compressor as your priority accessory. Lots of things the shops will sell you are optional but I believe if you are going off road at all, especially if it is somewhere even a little bit remote, tehn a compressor is essential.

Now take that Vitara out and get it dirty.

Duncs

There is a belt driven compressor available.

Are there any pros or cons with this type of unit or do they just do the job differently?

If you don't have big bucks, I would recommend the 'Pro-air" from bushranger. Retail is about $190.00

DON'T get a cheap nasty $50 jobbie. It will let you down when no one else is around for miles, its 40 degrees and your missus is ill and needs to get to hospital.

Get my drift.....just when you don't need it to, it WILL let you down!!!

Good thing no cheap.
Cheap thing no good.

You don't say which Vitara! I have an XL-7 and like all Grand Vitaras since about 2000, they have fairly low-profile tyres and the recommended pressure is 26psi. Now I think that's too low, at least for my ATs, and I usually run it at around 30psi on the blacktop (checked operation of 4psi rule, perfect). On dirt roads I usually reduce pressure to about 22-26psi depending on weight.
Choice of compressor depends on funds. I'm still using a cheapo, was around $50 I think. I just take my time, having a smoke between tyres to allow the compressor to cool down... Think I'll soon invest in something more suitable :-)