Dear carlodef,
You should recall that S-1 is a radar. The geometry on which the data is provided is the most simple one if you think at it from a radar point of view. It is a collection of echoes ordered in time and this both in azimuth and range.
This is the natural geometry of the radar and the most simple one to work with to fully exploit the product.
The side effect is that indeed depending on the pass (ascending/descending) your image might appear north/south (ascending) flipped or east/west (descending) flopped!
This is therefore not an orientiation issue but a convention that is followed by ESA (for ERS, ASAR and now S_1) and most of SAR data providers with the exception of MDA for radarsat (if I am not mistaken).
If you are not interested in the SAR timing (fundamental for application like INSAR) and want to combine your data with other sources (GIS). You have two options:
a) geoocoded/ortorectify the product, as mentioned previously using SNAP or other to project the data on our favourite world reference system
b) Open it directly with a GIS (open GIS) as the product are provided in geotiff, we provide a full grid of ground control points allowing openGIS/GDAL to geocode it on the fly
a) is by far most accurate as you can use also a DEM to correct for topographic and radiometric distortions induced by topography using the terrain correction method.