Also, sometimes it helps to keep your shoulders lowered, because if needed, when you decide to raise them, you can flip them over.

It only worked because your opponent was an idiot, not because you overwhelmed him.
If he raised his shoulders and extended his hips, he would've lifted you out of the dojo.

The key to aikido is control. It is possible to stay in control even while airborne, but much harder.

Keep your feet on the ground and push your opponent out. Alternately, you could go for arm breaks and stuff, but it's quite hard at 350 or so dt.

Basics for me is to keep your feet as close to the ground as possible and knock your opponent off balance as soon as possible.

I try to decapitate the opponent as fast as possible with helicopter kicks

i usually never relaxe anything below my abs, works well

If your opponent would have been a better player he could have made a throw-over in that situation. Like on this replay I attached. The replay is a bit glitchy but you see what I mean. I would suggest to try to stay on the ground.

My technique is to stay very low and grab for the feet. I think it works pretty good.