lantanas don't need too much water, especially once they are established. in the peek heat of summer, mine will get a deep watering once a week and that is only because they are on the same drip as other plants in the yard that do require a bit more then the lantanas. a rock garden sounds like a great idea. if you are looking for some xeric plants and flowers, check out high country gardens web site: http://www.highcountrygardens.com/ i think it might be too late in the season now to have orders sent here from them, but they have a great selection of xeric flowers, including various lavenders, that you can check out at their site.

Yes, that should be fine and enough to produce good bloomage. I grow some hydrangeas on the north side with no direct sun; the area around the plants is brightly lit by the sun though so, I would say my shaded area has a "bright" shade. The space on the picture may be tight for many hydrangeas though. But it hard to tell the dimensions from the picture. Measure how wide can the plant be without touching the existing shrubbery but assume the existing shrubbery has reached their mature sizes. For example, if those shrubs will get 1 feet wide when mature and that shrinks the available space down to 3 feet, look for hydrangeas that get no wider than 3' when mature. You usually want the hydrangea's width to fit in the planting space with some leeway... some separation between the hydrangea and the other plants. This improves the air flow between plants and minimizes fungal infections on the leaves.

For perennial suggestions come on over to the New England gardening forum and post your question there. You'll need to say more about the direction the house faces/how much sun and shade it gets. Any other info (how tall/wide the plants should be? Do you want the flowers to bloom in spring? midsummer? fall? favorite colors? open to shrubs?) would help too. For annuals I'd just head over to your local garden center and see what they stock for your region. The garden center will have them divided by sun and shade annuals.

Orange and blue each intensify the other’s color. If you want to make that floor look really orange, you pick blue cabinets. If you want to minimize orange, you pick a similar color, in a different value. Like SW Creamy. If you want to update without spending 7K having them painted, put that 7K into new lighting, and a different counter. You’ll get a much better result.