The Zinnas....if you have dried flowers still left, and you hang them upside down in a paper bag ,you can save the seed and plant next year.
The Dahlia bulbs you will have to dig up, shake off the excess dirt and store in an open cardboard box (seperate them so they are not touching) and store in a darkened , dry place, and replant next spring after all danger of frost. (Or you can plant them earlier in pots and place in a sunny window , then transplant outside after last frost.
I don`t recognize Vista Lavender (Salvia) If it is Lavender then it will probably come back...or if it is a preannual Salvia it will. If it is an annual salvia then it may come back from seed.I`d cut it back to within a few inches from the ground so that if its a preannual that it will be full when it starts growing next spring.
The Dianthus should come back. They are pretty hardy. I`d trim it back to within a few inches too....and be sure you trim the flowers as they die next year to keep the plant blooming all summer.
Lavender provence sounds like Lavender to me...and it is usually fairly hardy too. I don`t know if it is supposedto be trimmed though or not.
The Alyssum will not come back...at least not this last years plants.....but I always have seedlings that come up in the spring....hundreds of them! I have`nt had to buy any since the first year we moved here....and that was 9 years ago. i usually have tons to give away every spring too. They will come up in places where you may not want them, but I always leave them till the tiny plant gets it`s first flowers. they seem to transplant better at this stage.
Happy gardening! Sorry I don`t know anymore about the lavender.