Yes, I had one and I think is a great dirt bike to get started.

About 70 mph.

As I said in your other question to have a look at the 4 stroke 250cc but you are a good size and height for both the yz125cc and the cr125cc but you would also be fine on a crf250r or a kx250f

I think your friends have it about right. I like 2 strokes but in 2009 every one is going to stop making them and go to 4 strokes. if you wanted a 2 stroke I would go with a 125cc two stroke. if you want a 4 stroke, i would say no smaller then 250cc.

Agree with him, buy a larger one, and maby he will pay for a little of it after he rides it a 125cc-250cc is good nothing more

You are going to grow a little more before you wear out a bike. A 125 might be too small for you. I would look into a 250cc four stroke machine. Or I would look at the new KTM SX144 two stroke

Pressure from world bodies over noise pollution has stopped production on a couple of the well known brands of 125cc including Kawasaki and Honda. Popularity to race the 125cc has also been down as they quite often have to race against the 4 stroke 250cc and they usually get beaten (of course there is exception to that depending upon the rider onboard).
Part of the reason that honda developed the 150cc was to replace the 2 stroke 85cc although I don't know if it has been as successful as they would have hoped as the idea was for them to race against the 85cc and in America they don't allow that as they race in their own class. Australia has them racing against the 85cc.

A 125cc two-stroke or a 250cc four-stroke would be a good choice for your age and weight. Choosing between a two and four stroke is mostly based on personal preference. Each has their own advantage and disadvantage over the other. The most obvious difference is that two-strokes require you mix your oil with your gas. However Two-strokes are also lighter than four-strokes and have a much simpler design. It usually costs less to modify and repair a two-stroke engine than a four-stroke engine. But two-strokes can also be finicky and a lot less forgiving than a four-stroke if you don't know how to tune it properly. four-strokes also have a more user friendly powerband, they tend to make more power than two-strokes on lower RPM's so it's much easier to putt around and go as opposed to a two-stroke which tends to like being revved high. I personally prefer a two-stroke over a four. But you need to decide which would suit your needs better.

Choosing a brand of bike is the same also, whether it's Yamaha, Honda, Suzuki, Kawasaki or KTM. All manufacturers have their advantages and disadvantages over the other. Just keep in mind there's nothing that will affect performance, handling and reliability more than how you set your bike up, and how good of a rider you are. I've had friends on modified 250's and 450's get spanked by 8 year olds on 80's for that same reason.

So do some research and see which bike would suit your needs better. Once you buy your bike be sure to also get a repair manual for it and learn how everything works and how to properly set it up. You'll end up being safer, faster, and a better rider.

Good luck with your purchase.

Repeat repeat.
so it was snowing out?

I am 14 and i got a 55cc its tiny but its fast and fun and unless u plan to be doin heavy riding stunts tricks and crap like that then you'll be fine mines really fun but i live in a neighborhood ( it sucks i hardly ever get to ride!) its really fast so an 85 should be really cool have fun!