intraday - gain amount doesn't reflect in my cap. please help me understand

what is the settlement process of intraday trades? when does the profit really comes into my account?
does the brokerage charge applied for every order modification also?
is there an impact of leverage on the total gain amount?

The profit is yours as soon as you square off the trade however if you are referring to your profits being reflected in Q ( w.r.t fund transfer), that happens at around 8/8:30 pm.

No, brokerage charges aren’t applicable on order modifications.

Impact in what context? as far as the basic charges go, you will end up paying the same if you took a position with 1L as compared to 10k with 10x leverage.