Help me have crystal clear view on Margin shortfall doubts

hey i know i am asking too much question on this forum but i wanna clear my head before entering any new instrument. so apologizing for being annoying and yes this forum helped my clear 70% of my doubts so thanks to this community :slight_smile: but i have some question (maybe silly questions)-:
Q1) As of now if i know that span margin increases there is no penalty for client but broker right?
So what risks are involved (any margin shortfall) if client holds Naked futures short position (no calendar spreads or Synthetic call buy or anything relates to with hedging of futures) so is there any risk of margin shortfall considering the fact that the client provided the margin upfront to the broker before entering the trade?

Q2) Is ad-hoc margin applicable for lesser volatile (i mean not literally) scrips such as Index (Nifty) or reliance or currency futures?

This is the last and maybe a the most silly one and not related to margin shortfall -:
Q3) If i have collateral fund (Pledged) and the cash fund and if take any position( E.g-: currency naked futures buy/sell) from which fund it will get deducted first? because if it gets deducted from my collateral funds first then no worries, but if it gets deducted from the cash funds which i saved for hedging (options buy) or to settle MTM loses then it would be worry because as i know i cant settle MTM losses with pledged margin even if they are cash components.