New owner of an older Mercedes ML

[hightide]

I've just purchased a 98 ML320, my first Mercedes.
The first fours days I've owned it my wife and I put over 600 miles on it and are loving every mile. Since the wagon is the primary vehicle for my wife and child I want to pin-point every possible trouble spot.
My question is about general maintenance... warning signs like what to look for, and preventive maintenance.
The ML has 39,000 miles on it... and is an unmolested vehicle.(No accidents)
Here are my issues:

1)The battery is not holding adequate amps.
2)Small Leak in Front transfer case.
3)My Dunlops have some dry rot among the treads.
4)Wind noise after 70mph.

Are these indications of problems to come with any of the major components?
It shifts flawlessly and is a fun drive. The only downside is that she is just out of warranty.
Regards....
Mike