Given that Alucard leaped from a ruined Aircraft carrier into the middle of london, he us at the very least, capable of flight.
And if you had read my full post, you would have understood that I admitted it's entirely possible that becaude of how differ t Seras and Alucard ar e, they utilize their powers very differently. Alucard loves playing with his food, so we almost never see his full power. Seras is the opposite for the most part, so she probably goes full force.
That'd why we see Seras flinging warheads and artillery cannons everywhere while Alucard just likes to shoot/stab/eat everything. It's entirely possibLe he could use his shadows and strength like Seras could, but Alucard prefers to mix things up compared to her.
Regardless, we can draw the conclusion that Alucard is stronger than her based off two things, which I will elaborate on in a minute when I reach my laptop.
Event 1: Baldrick encounter, (OVA 1). Integra says (regarding Alucard's survivability), "Cut off his head? Pierced his heart? He is nothing like any vampire you've ever known. Your tricks won't kill him. You may be the fruit of the finest anti-vampire technology, but 100 years of the Hellsing family's accumulated knowledge produced this achievement. Our crown glory, the vampire Alucard!"
Based off of this, I think we can assume that the Hellsing family has improved his durability greatly, among other things potentially, such as strength or magical ability. I don't know whether or not that applies to his children, but I wouldn't imagine it would.
Event 2: Alucard vs Monster of God Anderson (OVA 8/9). Anderson has impaled Alucard, and Seras is attempting to stop him. Seras is barely able to hold back Anderson, but once Alucard reawakens, he is able to break free of Anderson, and then overpower him with ease.
In fairness, I don't think he *could* have unleashed Level 1 against Anderston without Integra's approval. He's *not* a vampire afterall, and not really an actual threat at the time. ... Of course, he also *wouldn't* have, unless the fight dragged on and he got bored of it.
I couldn't find anything about what exact criteria the Control Art has for lifting restrictions. Or really much about it at all. I do think he can lift all except Level Zero without approval, because IIRC he did so against Luke Valentine and Tubalcain Alhambra, without Integra's direct approval.