abillings

I have searched a couple of different sites, and it looks like I am going to have to remove and reseal the entire outside panel. Many of the posts were met with unsatisfactory replies to fix it or with replies from others who have the same problem. I don't want to take it to a dealership, because I know it will end up costing me a bunch of money and probably not even completely fix the problem. So if I were to reseal the outside panel, what sort of seal should I use? Is it something that I can get from an autoparts store or do I have to go to a dealership? Thanks

I have a 2001 Legacy with a nasty leak. Everytime it rains (which it rains 24/7 this time of year on the Oregon coast), water accumulates in the taillight region of the hatch door. Then when I open the door, the water flows out, making it very difficult to put anything into the car or take anything out. There was water INSIDE of the bulbs when I took them out to replace them. Is this a frequent problem with this model? Thanks