There is an example CSV file and an explanation of the file format in this article
https://www.jevents.net/frequently-asked-questions/importing-events-in-csv-format
The repeat pattern syntax is based on the iCal specification and it quite complex I'm afraid - see
https://tools.ietf.org/html/rfc5545#page-85 - perhaps the best way to understand this is to create some repeating events in JEvents in the pattern you want and then to export these and look at the RRULE field in the iCal export that is generated
Timezone : if you don't specify a timezone in your import then JEvents will use the timezone you specify in the JEvents config (on the iCal import tab). You should also specify a timezone on the first tab (which is used to define 'now' - i.e. your display timezone as opposed to the timezone of your imported data)
Hope that helps