The president is the commander and chief of the armed forces, so yes
Fleet is the highest, but is a wartime rank only.
Admiral is a higher rank than Captain. A Captain would be promoted to Rear Admiral. Then it is Vice Admiral, Admiral and Fleet Admiral.
In peace time Admiral. But there is a higher rank of Admiral of The Fleet used in war time.
In the Royal Navy, an admiral is a senior naval officer, typically in command of a large formation or fleet, and holds a four-star rank. An Admiral of the Fleet is a higher rank, equivalent to a five-star rank, and is a ceremonial position often held by the most senior officers, usually during wartime or in times of significant naval activity. While admirals can be active in command, an Admiral of the Fleet is rarely appointed and represents the pinnacle of naval rank.
The highest rank currently held in the Indian Navy is "Admiral" There is a higher rank "Admiral of the Fleet", hower this is an honorary rank issued only in wartime, and has never been given to anyone so far.
His current Rank is Admiral of the Fleet
Admiral of the fleet
The rank of Admiral is higher than the rank of Captain.
The highest rank in the US Navy is O-10 Admiral (4 stars). EXCEPT during wartime, when the rank of Fleet Admiral (5 stars) is attainable. A Captain in the US Navy is an O-6. Commodore is not used by the US Navy,
the answer is the Admiral of the fleet
(As this question is in the WW2 category, this answer is specific to WW2 combatants) "fleet admiral" can refer either to a role, or a rank. As a rank, "fleet admiral" was formally known as "Admiral of the Fleet" in the Royal Navy, Soviet Navy, "Großadmiral" in the Nazi Kreigsmarine, "Fleet Admiral" in the US Navy, and Marshal-Admiral (Gensui) in the Imperial Japanese Navy. In all cases, it was the highest naval rank in each country. Most countries seldom had more than one or two persons serving at that rank at one time. The exception was the US Navy, which had 4 serving Fleet Admirals by the end of WW2. The duties of someone filling the rank of Fleet Admiral generally would be considered Logistical and Grand Strategy - that is, they were almost exclusively shore-bound commanding vast collections of fleets of ships in far-flung campaigns, or heavily involved in naval production and procurement. As a functional role, "fleet admiral" generally refers to the commanding admiral of a specific fleet. It can refer to a variety of ranks of admiral, but, was generally not applied to anyone not at least of admiral rank; those of less than admiral rank who commanded collections of ships were usually afforded the title "commodore". If there were several admiral-ranked personnel in a fleet, "fleet admiral" would be the moniker applied to the one in command (usually the most senior, but not necessarily, depending on circumstances). The role of fleet admiral is a tactical command - it involves directing the operations of the fleet, according to the grand strategy directed by the naval command authority. A fleet admiral would have wide latitude of both action and authority to accomplish their assigned mission(s). Their command usually included not just naval vessels, but transport vessels, naval bases, marines, and sometime even non-Navy assets in the area of operation.
A Vice Admiral outranks a Rear Admiral. An Admiral is the highest peace time rank. Fleet Admiral is the highest during war.