Honda Repair: all dash indicators light up while accelerating.., honda accord coupe, worst case scenario

Question
I have a 98 Honda Accord Coupe V6 with 140K miles on it. All indicators on the dash indicator lights up when accelerating. I had it Honda diagnosed. Service dept says alternator is not providing enough voltage so that battery does not charge properly. They want to charge me $500 for a new alternator and battery.

Questions:
1. If problem is alternator/battery, shouldn't I have a hard-start problem (which I don't)? They just want my money probably.
2. I'm planning of replacing the alternator myself but I want to make sure that alternator really is the problem.
3. How much does a new alternator cost and is it hard to replace?
4. What is the worst case scenario for me if the alternator goes dead on me in the middle of the road? I am using the car for a short drive to my office.

Thanks for the help.

Answer
Boyet:
Eventually your battery will cause a no start condition. Probably your alternator is not charging the battery enough and is not completely dead. I would go with the diagnosis from Honda as it does sound reasonable based on the problem you are having. A new alternator from an auto parts store for about $200, Honda will charge over $300. It should not be too difficult as long as you have good tools and time. As for worst case, it depends on how much you want to gamble getting stuck.
Good luck.
Bill