Mixture of organic solvents are not preferred, better to use single solvent that will be more convenient in the future, if the technology transferred to the process/bulk synthesis.
Yes, Chlorobenzene is totally inactive at the hydrochlorination. You use it as a solvent and it will have high boiling point than chloroform and dichloromethane. If required you can reflux in higher temperature.
I am not sure about your second question. You can try and check. For similar reactions https://doi.org/10.1016/j.tetlet.2018.10.043