Hi, Although Sentinel1-A and 1-B are in 12 day repeat periods, your location is likely to be imaged more than once per 12 days. This does however depend on the acquisition planning. You can find the latest planning at https://sentinel.esa.int/web/sentinel/missions/sentinel-1/observation-scenario/acquisition-segments and then select the latest S1-A and S1-B kml files for displaying in Google Earth. For your location in southern India, the next acquisitions are both with S1-A on 9th July and 21st July at around 00:40 UT. There are no planned S1-B acquisitions for your location. So for the moment your site is indeed imaged 12 days apart but it will be worth checking future planning.
For the orientation of your corner reflector (azimuth and elevation), I suggest you use the following website: http://www.heavens-above.com. You will need to select your location and then select the satellite (number 39634 for S1-A and 41456 for S1-B). At this point you can save the web address for future planning. If you then select ‘All Passes’ you will see a list of when Sentinel-1 is above your site horizon. Then select the pass which will image your site, i.e. 9th July at 06:10 local time. You will then see a sky map showing the path of the satellite and at the bottom of this page is a table. This table gives the altitude and azimuth at maximum altitude. You can use these number (51 and 101 deg) to orientate your corner reflector. We orientate our CR using the elevation of the base side of the corner, in which case you need to subtract 35 deg of the altitude for heavens-above to give 16 deg.
If any of the above is not clear, please reply.
Peter