1. Do the car hire companies offer child seats for little infants.... ? Yes at an extra cost.
2. Would a taxi be a safer option ? Well if you think the drivers are nutters who is driving the Taxi.
3. Are the busses good enough to get around ? Well lets see more go by bus than go by car, My bet is safe enough, I take it your reffering to Dolmus buses? these are a great mode of transport andalso cheap.
The quickest, way to do this and the fastest aand the safest is to hire the car, Note less cars are on the roads in Turkey, This is because cars are very expensive

i certainly wouldnt drive a car around marmaris , the quiet country roads are 1 thing but some of the main town is horrendous, my parents live there and in the last 2 years they have had 2 people crash into them, 1 pulled out of a junction not looking and the most recent chap over was tearing it over a hill lost control and crashed into them, then got his mate to give his details in etc so looks like he wasnt insured either you need to have eyes in the back of your head, they are fairly crazy drivers, over take on blind bends, use their horn all the time, cut you up lots, only you can decide whether you want to try or not. my hubby hired a car last year around the bodrum peninsula and the roads were quiet so that was fine, even so i couldnt relax lol

We hire cars and drive in Turkey but you have to have your wits about you at all times. Drivers are unpredictable and I read somewhere that the death rates on the the roads are one of the highest in the world. We drive through Marmaris on our way to our destination which is much quieter and if I was staying in Marmaris perhaps I wouldn't bother. Parking is not so easy in high season. Also car hire is quite expensive - around 50 - 65 lira a day and petrol is around 3 lira a litre at the moment. If you are thinking about using it for a few trips out you may find that hiring a taxi for the day a few times is no more expensive. We had a mini bus on one occasion for a day with driver 120 pounds, there were 10 of us so it was a cheap day out. The local dolmus buses are very good but if there are 4 of us and it is a short journey we often find it's the same price or cheaper for a taxi.
If you do decide on a hire car marmaris-transfers.com are pretty good for both transfers and hire cars also pandora cars from Dalaman airport. We also have an additional annual motor insurance for 60 pounds to cover any excess, we get it on line. You will find that windscreen, tyres under body etc are not covered on the cars insurance and Turkish roads are often poor so you probably need some cover for that.

Thankyou very much for all your words of wisdom... ...
I will now sit back and decide if it's worth all the worry (insurance etc etc etc).
With it being my main holiday, and relaxation the main thought, I am thinking of using the bus.

Regards