If you put a straight thin capillary tube upright in water so it sucks up water from the bottom, no matter how thin, it can't draw water up above ~10m of water level.
xylem is not a straw, is no where near the diameter of a straw, and its[transpiration] is not about increased pressure its about decrease.
psi values at the apical mesenchyme are around -100 to -150 megapascals dependent on species and relative humidity at the stoma.
physics and biology although intertrined are not the same catechisms, heres a link toward most of m.j. canny's work.
https://www.researchgate.net/scientific-contributions/M-J-Ca...
here is is a basic scheme of things
Water Movement in Xylem:
https://oercommons.org/courseware/lesson/87595/student-old/?...
Xylem:
https://en.wikipedia.org/wiki/Xylem
Hydrogen bond:
a column of water is pulled by hydrogen bonding between molecules in a tug of war fashion, the top of the column is where water is dissociated from the column at such a rate as to maintain low pressure with respect to the column[xylem]
in summary water moves from bottom to top in a transpiration stream, that ultimately ejects water vapour from the leaves, resulting in a low efficiency mechanism, that loses a lot of the water but occurs at such a rate that the low efficiency is "good enough" for whats needed.
I don't believe this is correct, or rather is not a required component of the system but rather incidental. The chemical system within the leaf removes water via chemical reaction. There is a respiration process to dispose of waste gasses. Water vapor happens to be lost to this process not of necessity but rather because keeping it separate is quite difficult (ie requires significant complexity and additional energy expenditure). I expect that many desert adapted species approach perfection (but have not bothered to verify).
No they have different strategies to minimize water loss that comes with exhanging CO2 & O2 to the atmosphere. For example:
https://en.wikipedia.org/wiki/Crassulacean_acid_metabolism
Portulacaria Afra (elephant bush) is a nice example. It can switch between C3 and CAM photosynthesis pathways as needed.