Swaying, floating sensation after vipassana retreat

Stopping your practice temporarily would be a good first step. I would also suggest eating something grounding like meat. Maybe even have a beer or two. What you’re experiencing isn’t terribly uncommon - especially the rocking part. My guess is that during your retreat, you were probably overdoing it with the force of your concentration. This, coupled with a lack of good sleep can cause things like this to happen. You don’t want to have your foot so firmly on the accelerator.

Overtime, you’ll get used to the sensation of a calm and clarified mind. When you get a strong dose of it immediately, it can be disconcerting - like someone who has never been high before accidentally eating a plateful of special brownies.

You’ll be fine.

edit Didn't focus on the initial part of question, let's go step by step:-

1. That floating and swaying sensation arises due to mind accumulated in air within body. Air usually travels within body and if entire focus is made via that medium, these type of observations might appear.
2. TV felt like moving, same reason as above.
3. Felt like outside body, observation stopped inside.. this is mainly due to focus in space surrounding body, whose counter technique been discussed below. With me, it also accompanied with some colour in mind image like that of clear sky.
4. Arms & head movement:- yeah, with me I actually enjoyed this part the most, was amazed and wondering as how it's automatically coming back to meditation posture like a robot. Don't worry, this is just the subconscious state trying to wake.
5. About that rocking, swaying etc... It's a mixup of observation within blood movement, air etc. So it's normal too. Make sure to stop that music playing in mind cause the feelings associated with them or such circumstances in life that alter mood, usually raise a kind of happiness and sadness enhancing rocking, swaying etc.
6. Tricky part is don't let mind or yourself as of now, to blame others. Laugh on these, would be very easy to deal like this.
   At this state, it should be easy to divide mind into parts such that actual observer will be different and you can easily say that, "it was observed".

Hopefully, you have not been in touch (verbally too) with someone practicing at these states, and you didn't sit on any such meditator's seat. If so, ask them to give you maitri-bhaavna to make you come out of it and lower your "uneasiness" from this and practice this maitri-bhaavna via yourself too.

Previous discussion on counter technique for "infinite space state"
Incase if you don't stop practice or just wanna use meditatiom as remedy then below might be helpful.

Probably it's because of focus in sky or space or void around body with perception of subconscious state as "this sky is infinite". (In my local language sky, space void usually are same).

Refer to sallekh sutta of majjhima nikaya, this is known as akashanantyayatan.

From previous experience, this might be pulled back using anapana (start from 0 always, whenever stuck). Try to pull focus within cave of nostrils. If we draw a line around head in center of forehead and remove the forehead part then that particular line and area around that should be the area of observation which would feel relax when focus is pulled back to nostril cave.

This is cave because such was the feeling when did this, as if "I am standing inside the cave (nearby forehead) and air is coming towards me and passing back like something cozy side by me".

Also, better to take a day or 2 break, give mind something where it cannot stuck itself like do too much physical hard work, could be working with daily wage workers or in open gym (outside building) without music etc.