[Christ]

Will -

You have 3 cylinders, therefore, 4 main bearings. The thrust bearings will either be integrated with one of the mains, so the bearing will actually look like a saddle instead of a curved piece of metal, or it may also just be 2 half moon shapes (In your Honda, it's 2 half moons)

It will go in the area between one of the mains and the corresponding counter weight on the crank.

Why is it there? -

When you push the clutch, you're putting the weight of the clutch's pressure plate tension against the crank shaft, while the engine is running. The thrust bearing, appropriately named, prevents this from moving the crankshaft enough to cause misalignment and damage.

You'll see them when you pull the bottom end apart to replace the main bearings.

Rings -

Yes, just replace them. You'll still have to measure ring gap before installing them, though, because if you have to hone the cylinders, that will increase the cylinder's bore by a small amount, which could set the ring gaps too wide. The ring gaps could be too small, as well, in which case, you'll need to file them. Always file from the outside in, so you don't leave burrs, which could cause damage to the cylinder lining.

Bearings -

Also, replace them all. Normally, you'd have marked the cylinders as you were pulling them out, but since you're replacing the rings and bearings, it's not as necessary. I just hope you bought the right size bearings, because there should be markers on the crank/block to tell what each bearing size is that goes in each bearing bore. They're not always just standard bearing size.

That's all for now.