Re: milaad
this is simple arabic term, if i’m not wrong, i heard this from some aalim too… literal meaning of this word “bid’ah” is this ==> discovery, invention, and creation i.e. forming something without any previous sample… like we call ALLAH :swt: “Badee’uz Zaman” because HE created this “Zamaan” when it was not present, and there was no sample of it, it was created for the first time.
now when you use this in religious context, it obviously means “by sample” we mean the “way” or “act” of Muhammad 
and his fellows rizwanallahu alayehem… so the definition of this term which TLK mentioned seems quite right