WAV is uncompressed. MP3 is highly compressed, but lossy. FLAC is compressed and lossless. If you wanted to store lots of master copies of audio, you could use WAV or you could reduce storage space by using FLAC instead.
So basically, if there's a distribution of possible outcomes (with estimated duration plotted on the x-axis, and probability on the y-axis), then we put bounds on either side of the distribution and take a 'central' point on the x-axis between them. But instead of a simple average, we can use a log scale on the x-axis, so that we represent estimates of different magnitudes well. Now the simple half way point on the x-axis is on a log scale, and (I think) equivalent to the approach you described.
So one question here is: Why reduce the distribution (with long tail or whatever) to a single estimate number? If the distribution represents the range of possible outcomes well, then the single number throws away most of the information in the distribution.
Yes, I don't see the logic of using fertile agricultural land for solar PV. It seems like short term thinking and a planning failure. I've heard at lest one similar story regarding reforesting, i.e., a scheme that was planning to use fertile land in Wales that was ultimately canned due to local objections/resistance.
For the battery storage, perhaps they will ultimately choose https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery. The cable manufacture seems like more a 'when' rather than an 'if' problem. The scheduled first phase of construction is 2025-2027, which we can reasonably expect to be delayed by 2-3 years if they are trying to build new manufacturing capability. Overall this still looks to be in the realms of possible/viable IMO.