Old system when I fought with old SA and Ka-Tet (late 05-beginning 07), fleet would have a FC, Fleet Commander, this guy normally has lots of experiance in fighting fleet v fleet engagements. Massive fleet fights are very tactical and FC's need to be on the ball if they're going to win. I actually have held the FC position in a few fleet engagements...it aint easy lol there are a lot of things to consider.
Fleet fits...on an Alliance scale with a mix of POS warfare and Capitals you will find that sniper fitted BS (megathrons, Rohks, Apoc, Geddons, Hyperions, Tempests, Maelsturms etc) forms probably 80% of a support fleet numbers.
Once the engagement begins, all BS are normally sniper fitted 150km+ range all engage the primary target...this is called by the FC who has a 2nd and 3rd back up target callers incase he himself is popped. Secondary and Tertiary targets are also called so that when the primary does go pop, fire is switched to the secondary, which is now primary etc rinse and repeat until either you force the hostiles from the fight or your fleet has to pull out.
These can be a lot of fun...but I'd say most of the system attacks and defence I have taken part in 80% of your time is spent sat 'waiting'.

Any you contribution in a fight could last only 30secs if you get called as a target by the opposing side! You tend to die very quickly if you have 30+ BS shooting you lol
Very 'cheesy' vid I knocked up back at the beginning of 07 in 30mins on youtube

just type tekno eve tribute into the search.