Due to the enlarged suckers i would venture to say it a male......However I am not sure if it is a Vulgaris or not, the arms seem alittle too long.... Being that you are from Sweden, im going to guess this guy came from the Mediterranean, is that true? . IF it is a vulgaris it would be most likely be pretty young as Vulgaris grow to be fairly large, My best inaccurate guess since size is a terrible way to tell age, but i would guess between 3 and 5 months old.
I'm not really sure where it comes from tbh and De Jong said it was a Vulgaris, but I find it more resmbles A. aculeatus and considering two arms seems to have been lost maybe that's what it is?
I'll try to get a reply from where it came from.
My immediate impression was that this is not vulgaris. The eyes and mantle don't look at all like what we see in the US variety. I think your thoughts about an Indonesian animal are much closer. It would be good to find out as the temperature of the tank will vary considerably as the Indonesian animals live in much warmer waters.