Weather Stripping and Pillar Sticker

I have always had problems with air coming in in cold weather on my drivers side and the dealership always said they could not reproduce and wrote it off. But now all the stripping at the bottom of the window, as well as the black sticker between the two doors is completely cracked and split. I'd like to have the stripping replaced at the top too though since that's where I can hear the air. Is this something I can fix or does it need to go to a shop? I have no idea how I would get the old sticker off since it's all cracked and peeling, nor how to apply new stripping or where to even get this stuff.

Thanks!