Afternoon sun is going to be very restrictive......most hydrangeas would prefer afternoon shade at the very least. If you can, I'd suggest planting on the east or north side of the residence. If you can only plant on the west side, then the only hydrangea type I'd recommend are the paniculatas, which tend to be the most sun tolerant species. Even then, these will need routine deep watering during the summer months.

Clay soils are not that difficult to work with provided you go about it properly :-) Dig wide but very shallow planting holes, scuffing up the soil well and plant high. Do not add amendments to the backfill but mulch with whatever you prefer to the top of the rootball.

Hmmm, I cannot think of a hydrangea that will do well under those conditions. I would suggest growing them in containers and placing the containers where they can be watered by drip and where they get morning sun and afternoon shade. Your afternoon sun and mine are too strong on the west side of the house and the clay soil is bad for the roots (will need to be amended as they like well draining acidic soil or else they can get root rot).

I am concerned about your wanting low maintenance though since container plants need more water than plants on the ground, will need more frequent fertilizing and you may need to bring them into a garage during the winter months.