I'm hardly a peach tree expert, but I did work on a peach/pear/apple Orchard for two years before I was 18 and learned quite a bit about them just from over hearing and seeing things.
Like Leslie A. said, you have to thin them if you aren't already. As soon as the peaches are a little bigger than the eraser on the end of a pencil is a good time to get out there. Go along every branch and just pinch off the peaches and leave one peach about every 8-12 inches. That will give them room to grow, and they wont be fighting over nutrition. Pears are the same way.
Thinning apples is a little trickier and I'll share my knowledge there since I'm new and feel like typing. Wait til they are about the width of a dime, and go along and spread them out about every 12 inches. But the problem with apples is each spot can have about 3-5 or so apple buds. You thin out all the buds except for the biggest one, which is commonly reffered to as the 'king' bud, because it is the biggest. That way you only have one king bud about every 12 inches. Makes for nice big apples.
As for the red spotting, how big are the spots? If they are really really little spots of red, and hundreds of them, so much so that they turn the leaf almost a rust color then it might be aphids. I think they were aphids anyway. Three years ago right after I started out there in the orchard we had a really bad aphid (I think it was aphids, don't quote me) infestation and I remember them callin' it rust something. I'm not really sure about all that. My area was thinnin' and pickin' and not so much playing tree doctor.
Regards,
Kyle