Multiple filters - file extension

Question

1. I have an use case where I should search for files in sharepoint library and filter files that start with ABC and the file type as CSV. I have the below GET command but I am not sure how to add another filter that picks only the CSV files.

   https://graph.microsoft.com/v1.0/sites/company.sharepoint.com,U265b60,346a1581/drives/driveid/root/children?select=name,@microsoft.graph.downloadUrl&filter=startswith(name,'ABC')

2. Using the above @microsoft.graph.downloadUrl is there any way to find the number of columns present in the csv file?

Thanks