The buds failing to open and dropping off are usually the result of being too dry in late summer when the buds are forming. As for the dead leaves; it is often caused by the early morning sun on the wet or frosted leaves. This probably won't be the case if it's protected. So as there are only a few leaves dropping, I would say that even evergreen shrubs will lose some leaves during the year.

I suggest too dry in the summer and subsequently too dry now. does it get winds blowing through the porch area?
if the water drains freely through the bottom of the pot you wont overwater it as it will drain away, unless it is sitting in a deep saucer.

Thankyou for your replies. Yes I suspect it is my lack of watering & feed. I hope I can remedy these & the camellia recovers