I’m not aware of the US sending disposable munitions to Ukraine, enlighten me.
Ammunition has a shelf life as it degrades so it's all disposable, and old equipment gets replaced by better modern versions, so when the US sends older equipment to Ukraine, the US upgrades their own stock, which they do anyway.
What repayments are US expecting from the aid it sends, apart from a share in their resources?
Firstly, some loans given to Ukraine are to be repaid. eg https://shorturl.at/YkTox
Secondly, what do you mean, apart from? A share in resources is payment for aid.
What huge profit is Trump personally expecting?
Trump hasn't divulged what he's personally going to gain (why would he) but the US have give $106 billion in aid to Ukraine so far, and Trump has asked for resources worth about $7.5 trillion in return. Why should the US profit from helping a democratic country that's under attack? The UK and EU don't expect to get their donations back, let alone make a profit on them.