1 ) I get stake if based no number of block moved or based on number of days i stake coins
2 ) if i stake 10000 coins if it is 2% ROI i get 2% of 10000 coins right if mentioned blocks moves
3) how APR is calculated ??
1) depends on the coin, most seem to be time staked
2) if ROI is 2% you'll get 2% of what you stake, yes
3) depends how often stakes are counted etc and for how long you stake, if you receive 2% every 3 months then ROI would be 1.02^4 in percentage terms which is a little over 8% assuming you reinvest stakes.
third point
i must not withdraw the stakes so i get 8% right