Acts1:9 - After he said this, he was taken up before their very eyes, and a cloud hid him from their sight.
How do you know Jesus ascended of His own power? Scripture simply says "he was taken up". It doesn't say that how.
I will concede that it was likely His power, as He was given all authority. But the point is that you're inferring and have no supporting evidence. The same argument goes for your position on Mary's supposed assumption.
Jesus said, "I and the Father are One." Which is supported under the Trinitarian dogma. So, this would seem to be a moot point, by the Power of God, Christ Ascended into Heaven. What other Power could have brought the Lord into Heaven?
Leaving aside your disbelief in the Assumption of Mary, nobody has ever suggested that she was Assumed by anything other than God's power.
Because he was God.