1. We had an idea to leave the current posts, and cement in new posts in between.. the back of the fence is shielded by trees so looks aren't important. This plan would allow us to shore up the fence long term without a ton of work digging out old posts and concrete. My experience with replacing posts is that it's extremely difficult to get a good line up with the existing fence boards when you reset the new post, and I'd prefer to keep the existing fence boards in place. Granted, the new posts won't be at the seams, and years from now we would probably need to replace the old posts, but this plan would buy us a lot of time and be pretty inexpensive. Is this ever done?

2. What's the best way to protect new wood posts from eventual rot at the ground level? I was considering buying some vinyl post jackets and just cutting them above the ground level, so water running by won't get on the wood. Are there any other ideas or clever tricks people use to make these fences last a long time?

As always thanks for taking the time to read and post any suggestions, it is much appreciated.

Steve

as to preventing rot, use PT posts and make sure you put the post in the ground first, then a layer of gravel, then pour the concrete. this way water can drain away from the post. remember that wood is pourous and the water that hits it up top will week all teh way to the bottom of the post. if it is 100% encapsulated in concrete, it starts to rot.