Virtual Assistant for Shirt business

Im searching for a virtual assistant that is capable of doing niche researches, writing of listings for T- shirt designs.
Therefore, please explain if you have experience in research, what kind of research tools you are used to work with and give some examples how you would generate the listings for me (what your way of working on these is).

The niches and listings should be on the one hand side suitable for the US market and on the other hand for the german market.

Please let me know your hourly rate and also how many niches and listings you are able to create per hour.
Target would be 10 niches incluidng listings per hour.