Vibrato
This element represents the hallmark of the Romantic violin, but it was not such according to sources such as Campagnoli1. How and when to use of this expressive tool varied a lot according to the region and the individual, but it seems like it was only discreetly used to emphasise special moments, such as long sustained, or long ending notes.
The unsupported violin setup did not allow freedom of the arm to make a wide upper arm vibrato, as one would have to hold the violin with the thumb. In addition, excessive vibrato on gut strings produces an undesirable effect on the sound. Hence, as Stowell summarises2, the aim would be to acquire a variety of vibrato of different speeds and intensities to suit and add up to fulfill the many expressive requirements of the music.
Cadenzas
Baillot explains in detail what types of cadences, and gives several examples of how to build one4. In our case, the one that fits into this context is the tenth one: "Returing to the theme without interruption and being linked to it by what is called a re-entry".
This example would be illustrative for this purpose:
BAILLOT, Pierre (1834). L'art du violon, Paris: Mayence, Les fils de B. Schott , p. 177