Hi John,

It's tough to say absolutely for water use, since many plants will use as much water as you give them (within reason)--determining the tolerances is not always the focus of horticultural research.

Of the trees you listed, the junipers are certainly the most drought-tolerant; requiring no supplemental water once established in most cases.  They are followed by the spruce, pine, apple, and maple in that order, and distantly.

Of the shrubs, the lavender is most drought tolerant, being accustomed in its native Mediterranean range to receiving no water during the summer months.  Good drainage in the winter is important, too--they don't appreciate sitting wet.  Butterfly bushes are reasonably drought-tolerant but typically require supplemental water; the dogwood will need regular watering.  The grasses you list (at least to look nice) are are probably similar in water needs, with the Avena grass perhaps having a slight drought-tolerant edge against the other two.

Information about size, which will depend somewhat on growing conditions, can be found in these CSU fact sheets, along with ample other information that you might find useful:

https://csfs.colostate.edu/wp-content/uploads/2024/01/Large-Deciduous-Trees-Fact-Sheet-7.419.pdf

https://csfs.colostate.edu/wp-content/uploads/2024/01/Small-Deciduous-Trees-Fact-Sheet-7.418.pdf

https://extension.colostate.edu/topic-areas/yard-garden/ornamental-grasses-7-232/

I hope this is helpful!

Cordially,

John