Yeah, I see what you mean.
So, you don't want an archive?
What are your reasons for not wanting to use mysql? (No mysql server??)
All the stuff you have listed is pretty easy (especially with PHP).
Open the file, count the number of row returns (each entry would have to be on a line, NO line breaks).
And just put each line into an array. Then use that Array for all the stuff you want to do, manipulation, deletion etc. Then just output the array to the text file.
The automated deletion is easy with this, just count the array, if it has more than 7 (8, start counting from 0) keys, delete the oldest.
If you would like more help with this, I don't mind putting a little time forward with you. 😉
Lemme know if you have ICQ, AIM, MSN, YIM etc. We can talk and we'll get this worked out.
-Travis