Information about individual varieties you have asked about:
Agapanthus: Overwinter all varieties with leaves in a bright, cool place at a temperature of 5-10 °C. Water sparingly - only as much as is needed to prevent them from drying out. Varieties which lose their leaves can be stored in a dark place and don't need to be watered. Re-pot every two years in the spring.
Thorn apple/Angel's trumpets: Take inside before the first frost; if the plant has been slightly damaged by frost and leaves are falling off but the stronger wood is not frost-damaged (brown and soft) it is still worth putting it inside for the winter. Prune as little as possible, the more you cut back the later the plant will flower next year. Overwinter thorn apples in a bright, cool place at temperatures of 2-5 °C. If it is kept in a place which is too dark, it will shed its leaves and sprout comparatively late in the spring, which in turn means it will flower later. Water plants with leaves in moderation during winter, just enough for them to survive with foliage and water bare plants sparingly to keep them from drying out.
Gingko: In a pot it is more exposed to frost hazards than in the ground and for this reason it is best to put in the garage or take it out of its pot over the winter and tuck it up in a protective position in the ground. If you have to keep it on a balcony over the winter, wrap the pot and the plant up well in fleece (not film!).
Herbs: Parsley, lemon thyme etc. can stay in their bed. Curry plants and lavender cotton are best kept in a bright, cool, frost-free place at a temperature of 5 to 10 °C.
Daisy bush: When putting this plant away for winter prune about a third of the plant. Overwinter in a bright place at a temperature of 10-12 °C and water in moderation so that it doesn't dry out. Put into fresh soil in the spring.
Passion flowers: In mild climates (wine growing climates) and if planted in a sheltered location, passion flowers can usually remain outdoors. There they will withstand temperatures down to -5 to -10 °C if they are well established. Otherwise, take them indoors and store at a temperature of no more than 10 -12 °C if the outside temperature is between 0 and 5 ºC and water sparingly to ensure that they don't dry out. Note that there are different varieties of passion flower, including ones which don't like heat. These, like tropical plants, need to be in as light a place as possible and at a temperature of 20 °C, and kept consistently moist.
Citronella plant: Overwinter in a light place at a temperature of approx. 10-15 °C and water occasionally in moderation.