よ〜! i don't think you're stalkerish at all! i'm sorry i just added you without responding to your message either, i just saw it now. xD; but thank you for the invite! i'm super happy to meet another fan of this amazing culture. よろしくね☆
Senior members are basically just people with a certain amount of posts. Junior members work the same way (I think like less than 100 or something like that)