I am downloading Forex historical data on USD/CHF (1Minute chart) from DukosCopy, which contains columns Open, High, Low, Close, Volume

I've just recently learnt how the price works - through the Depth of Market - a.k.a. 'Level 2 data', where agressive buying fulfills many sell limit orders. Similarly, agressive selling fulfills fulfills many buy limit orders. As I understand, these are what move the price.

What's strange for me, is this entire file is for the Ask data only. It's also possible to download a similar file for Bid data only.

Question:

1) Looking at the above image for the Ask (prices that a seller is willing to receive), Why High is so close to Low? If I interpret it correctly, High means "the highest possible sell limit order witnessed at that time". I would assume at least 1 person having a limit order sitting at some ridiculous place, like '5.1234'. The volume of 96199996.9 LOTs surely will have someone like that - thus, High should be far above Low?

2) Or is it the highest limit order that was fulfilled, not merely awaiting? (Thus it's somethng similar to 'Time And Sales' of MetaTrader 5, aka Level 1 data)

3) A total-beginner question - are these values already including the commission of a broker that provided such a historical data? (is it already embedded in these numbers? Is it a simple offset of O H L C?)

-Edit: I now think that Open, High, Low Close are prices which had the best-available limit order (non-fulfilled yet). However, in that case, why don't we then have the OpenVolume, HighVolume, LowVolume, CloseVolume. What does the "Volume" mean in our case and why does it suffice?

4) Would the Volume be more useful had I selected 'Ticks' instead of '1 Minute' data?