I would grab the chance of having a gorgeous Azalea (would have to be in ericacious compost): great choice of colours, but not scented. For scent, one of the best is Daphne bholua. I also have a lovely fragrant dwarf lilac in a pot, but it's not evergreen!

Tricky question - I hope you get some good ideas here.

Just seen Sarcococca hookeriana var. digyna in "Evergreens", one of Andrewr's photos; it has a powerful scent. And another flowering evergreen is Viburnum tinus, but to keep that in a pot you'd need to keep it pruned.

How about Raphiolepsis umbellata? In a pot, it shouldn't get too big.