Officers' duties during the age of sail?

I don't have a link, but if you have more detailed specific questions, I'll try and answer them.

From knowledge on the Royal Navy (1792-1815) i know that,

Admiral of the fleet - he had the last say on orders of battle and the general strategy what the navy was going to play

Admiral - had total control over his squadron and would mainly be giving commands to friendly ships and officers during engagments

Vice Admiral - he would lead the main a front of a naval engagement whilst being overseen by the admiral

Rear Admiral - was the senior command of a naval squadron and overseed all actions and welfare under him. He would command from the centre vessel, he would also be the most junior naval admiral.

Commodore - A captain assigned squadron command (several ships) strategies in engagements / meetings with senior officers were given out with squadron orders and assignments could be set. A commodore would be commanding his own ship or have a captain serving under him on a ship.

Captain - This is usually the most senior officer on the ship who has control. He would of made sure that the general running of every dept would be sufficient and up to standards for battle conditions and journeys at sea. Sometimes you might hear the phrase 'post captain' which basically meant a captain who had a post (ship) as sometimes during peace times captains of ships were demoted simply because there was no commands availiable and then were 'posted' to a ship becoming a captain again.

Commander - this title could be given to the most senior rank on a ship.

Lieutenant - this is were it becomes interesting as you may of well known on bigger ships (ships of the line) there could be as many as 4+. The reason is fairly simple there are groups of men split into divisions each with a lieutenant overseeing the men and obviously the more men the more lieutenants that will be needed. When you start to see 1st/2nd/3rd/4th etc before is simply a reference as to their seniority amongst the ship for example the 1st lieutenant would be the most senior (as he would of been commisioned as a lieutenant the longest). Most watch officers would of been lieutenants as well.

Midshipman - was the most junior officer usually a boy who gained acceptance onto a ship through connections to the captain of the vessel or other means. His duties were mainly to watch over a division along with lieutenants in battle (group of men and guns) and working with senior nco's to achieve the daily running of a ship...more or less like a supervisory role amongst nco's.

There were rear admirals / vice admiral / admiral of the blue white and red (I think they are the colours) with the rear admiral being the least experienced and usually commanding the van squadron so that he wasn't leading the fleet into the engagement. Then in some cases the admiral would command the centre squadron leaving the vice admiral to command the leading squadron.
When in battle fleets were usually arranged into 3 squadrons each with an admiral as the co meaning he had around 15-20 ships under him. Although examples like trafalgur don't follow this at all with the 'nelson touch' two columns were formed one by nelson in his flagship hms victory and the other by collingwood in his flagship hms royal sovereign. Both these ships were 1st raters with over 100 guns