Deleting will become an issue...
http://forums.mysql.com/read.php?20,253717 (Very slow DELETE, UPDATE, INSERT on a new server)
http://forums.mysql.com/read.php?115,251243 (Performing multiple updates and selects)
http://forums.mysql.com/read.php?22,246868 (mysql very slow after million insert/delete)
http://forums.mysql.com/read.php?26,247225 (Statement/row questions)
Summary tables -- to may the reports fast...
http://forums.mysql.com/read.php?125,252723 (Database Design for huge set of data)
http://forums.mysql.com/read.php?10,252593 (Counters)
http://forums.mysql.com/read.php?125,245133 (Design approach for summary table by 3 items)
In Data Warehousing, one should "Normalize" out common strings and put them into "dimension tables" rather than have them bulking up the "fact table".
Indexes... It is very hard to see the indexes from what you provided, please
SHOW CREATE TABLE tbl\G
and surround it with [ code ] and [ / code ]
We can chat some more after you have a chance to glance over that stuff.