Re: Zwift being easier than real life - I see this a lot with people I know and ride with in real life. I think it is a result of the power broadcasted by their smart trainer being inaccurate (regardless of doing a spin down). They are generally 2-3mph faster on Zwift as compared to a similar real life route/distance and elevation.
It helps if you have a trainer that can be calibrated with a real power meter (if you use a trainer bike without one), or use a bike with a power meter that you can connect directly to Zwift. My experience has been inside watts (real) are harder than outside watts because there is no micro recoveries (ability to freewheel without loosing momentum is at a different rate dependent on trainer flywheel). As a result, the ability to hold a certain wattage over time is shorter because there is no micro recoveries. In other words I have to work harder than I would outside, which is fine because when it comes time to do it IRL where it counts, I'm much better.
If you want the most realistic experience this is the smart trainer to use. Aside from real inside watts being harder vs. outside watts, the riding experience is just like IRL. You can also adjust the trainer to account for wind speed through it's app.
Inside Ride - E-Motion Rollers