tulips naturally grow in rocky soil that gets baked in the sun. I see no problem. give it a go.
Are you bringing them back in soil with roots, or as cuttings? Cuttings need to be shaded until they have formed roots. Bringing in plants in soil could bring all sorts of diseases into the country.
The blue one has flowers like a lithodora or lithospermum, but the leaves don't look right.
The builders bags that are approx 1 m cube hold a tonne of gravel etc. I would consider 4 cubic metres to be 4 tonnes.
I saw the film on the tv last week. Now I know where hubby gets his "Feed me, feed me NOW" from.
I bought one last year in Lidl. I repotted it and it went crackers. It spent the winter in my mums conservatory, then got chopped, and is currently on a 4 ft pyramid. Not bad for 4.99
Looks like Datura stramonium aka Jimson weed or thornapple or even Devils trumpet.
The seeds are highly poisonous.
Looks like a privet flower bud.
Brugmansia do that. It is exacerbated by spider mite, if your plants are in a dry spot.
I have to say that I like bright clear colours in Spring. I had some Purple tulips as part of an offer a couple of years ago. In dark dreary days, they got lost. A bright yellow or red or orange is much more cheerful.