>

The cruise missiles, fighter jets and drones they have used constantly at the levels you are citing, or more. They have lost 184 independently confirmed fighters. So likely 2-3 times as many in reality. Which isn't sustainable. Same with the Ukrainians. AA is dominant in this war, and no one has air superiority, hence no heavy bombers. 
The Black Sea fleet has been heavily used, especially for cruise missile strikes. Ukraine sunk the flagship and heavily damaged at least one other ship. 
You aren't a terribly effective propaganda outlet.
What kind of armaments do you imagine Ukraine having that could make a harbour unusable? 
They might be able to take out a few warehouses, maybe a bit of rail or if they hit the harbour with everything they have a pier.
You need some serious tonnage to make a harbour unusable. Like nuke scale tonnage and even that would probably only make the harbour unusable due to radiation. It's like trying to sink a piece of land. >

Send in divers and plant mines? >

Damage a ship, or maybe two? Before the harbour is cleared by Russian divers. Not at all a bad idea if the Ukrainians have the means. But it will in no way make the harbour unusable. >

It would not endear the residents of Crimea to Ukraine if it ever regained the territory. And I don’t think Ukraine’s military situation is at all desperate enough for such a move. >

Ukrainians aim to retake Crimea . Blowing up the bridge between Russia and Crimea have caused a collapse of Russian Logistic . They can't supply the troops in Crimea and southern front ( due to rail there being in range of Ukraine weapons ) to be in any figthing shape . 
They even made sure the bridge is just partially damaged to allow Russian forces and sympathizers to have a retreat option like in other operations . >

This is the answer - blow the fucking bridge. With it gone, the Port becomes very limited in functioning since all the supplies for the port come across the bridge. It would also make Russia's position in the south untenable. >

They already did . A truck blow up a while back on the bridge making it too structurally weak to move a train on it . 
Without rail transport  , Russians can't supply their troops in dependable fashion since they lost most of their military trucks early in the war and had to commandeer civilian ones . And transport ships make too much of an easy targets for most weapons including drones and missiles . >

Same question as why they would ask for cluster bomb munitions, something that would tax their rebuilding efforts after blowing up Russians- what's to lose? Pootin has not waged war against a cogent enemy, he has acted in pissy-pants temper tantrum missile barrage after barrage of retribution, trying to wipe out the people he can't conquer. So what if Sevastopol is destroyed in the attack? Mariupol? Crimea? At this point, the whole country will have to de-mine, dig out, and rebuild; Ukraine is the people and the dotted lines across the earth are just markers in a bloodbath against a dying asshole. >

and the residents of the Republic of Crimea who do not want to be slaves of the Kiev regime, as under the Communists, who are they? >

It would probably greatly escalate the situation and we would probably see ukraine getting carpet bombed heavily.
Russia has been greatly holding its capabilities back. We are painted a picture that is not reality. >


Russia has been greatly holding its capabilities back.

Nukes aside, it really has not.
Russia just isn't as militarily strong as we all thought a year ago.  It's a lot of cool looking prototypes that are just that and logistics that a third world country would be ashamed of.  It's not looking like the second strongest army in Ukraine for kicks.
Edit:  I'd like to explain why this person's reply is also wrong but they blocked me.  I didn't say anything offensive, so Russian pushing a narrative I guess. >

Russia hasnt used its airforce and navy thats in the black sea. How anyone can claim they have used their full capabilities is beyond illogical when we havn't even seen their air force leave the ground. 
Russia hasn't sent any bomber planes up yet. You truly believe they couldn't send up 100 bomber planes + 300 cruise missiles + 50 fighter jets + drones? 
Most people fall into the group that believe ukraine is shooting down all russian missiles yet at the same time have no power and their energy infrastructure is bombed out. Its illogical and a testament to the propaganda we are witnessing.
Russia could bomb ukraine off the map at will anytime they want. They can bomb anywhere they want anytime they want. Why aren't they doing this? Well despite the propaganda russia doesn't want to kill everyone. These are very pro-russian areas. Why would they kill everyone? most of these people speak russian and 3 million have gone to russia.