I would be cautious about using the id-1 and id+1 for navigation. This could really get screwed up if you deleted a poem. For example, if you have 3 poems ( id 1, 2, and 3) and you deleted # 2, then by clicking the previous button on number 3, your result set would be empty, since #2 was deleted.
Also, the external text files probably wouldn't work either since it sounds like there are just too many... Searching for "Pagination" is the best thing... There was recently a post that had excellent help in it. (within the past week).
Good Luck.