Yeah you're on the right track but have some misconceptions.

Time is a measurement of causality. Lightning strikes, then you hear thunder after a certain amount of time. So time definitely does have a single direction, otherwise things could happen before the event that caused it to happen. E.g. you hear thunder before you see the lightning strike, which is completely unphysical. It's kind of impossible to think of a universe if time could move both ways. What's also interesting to think about is without events that cause things to happen (if nothing happened), how can you measure time? Does it even exist then? This whole premise of causality, along with the discovery that light travels the same speed no matter how fast youre going, eventually led physicists to come up with special and general relativity.

What you're talking about with spacetime acting like fluid is just a property of waves in general. It isnt that spacetime is a fluid, it's that both spacetime and fluids (liquids, gasses, and plasma) are what physicists call "media" for waves to travel through. A wave is just engery moving through a medium. And youve even said it! The medium wants to stay still, and this restoring force is the whole reason why waves exist, why energy can travel. There are a bunch of media:

• Matter (solids and fluids) is the medium for sound (compression) waves or waves that move up and down like water (transverse).

• Electromagnetic field is the medium for light (photons).

• Spacetime is the medium for gravity. (General relativity implies gravity is the bending of spacetime).

• The Higgs field is the medium for the Higgs boson.

• Crystals (or solids in general) even have little waves traveling through their molecular bonds called phonons.

• Quantum Mechanics describes everything as a probability wave.

The list goes on and on. If you're interested, look up wave theory. Or if your more interested in how special/general relativity came about, look up the Michelson-Morley experiment (We used to think light traveled through a medium called the "ether". This experiment drove them mad when they couldn't prove it, but their findings were huge and led us down the path to our current understanding of spacetime).