Anyways, 2 first queries optimized, one less table to lookup, indices being actually hit. Far from being completely optimized (still a filesort happening!), but should proof to be an order of magnitude faster, DESPITE hitting more rows. I have NO way to test however, nor profile correctly due to lack of dataset size, so measurements would be less than error of margin.
Replace admin/index.php 2 first queries with those found at:
http://pastebin.com/hwncLV1wLooking at the image below, I fail to see how your 'optimized queries' are better. Maybe I just don't have a full grasp of the EXPLAIN command from phpMyAdmin, but it looks to me as your query scans all rows in the index, which comes out to 2436 with my current data set. That is way more than what the query was scanning before. Please correct me if I am wrong in reading the output. I only looked at the first query and stopped to get clarification.
http://i.imgur.com/G4bJM.png