spray some graphite in the key hole. It should help for a little while. If your key is not the original, it may not be cut exactly right, causing it to stick a bit. No big deal, as it is used, it'll wear in.
As for the buzzer, it should be under the drivers side dash in those years. Just open the door, follow the sound, and pull out the buzzer. Thats what I did to mine ('91 pickup)
