Say for ex. I place a limit order for ACC Ltd at 1550 a share for 6000 shares. Will I get my order fulfilled ? What happens to the share price then? Will it go up or down ?
Say currently the price is 1551, you have placed an 6000 shares BUY LIMIT order.
If someone is willing to Sell shares at 1550 he places a SELL order at 1550 say for 1000 shares.
So now, 1000 shares what he is selling will be bought by you, for remaining 5000 shares the system will be waiting until someone places a limit order Sell at 1550. Otherwise if someone is putting a Market Order sell, he wishes to sell at any price, so that case also your order will execute.
Mostly for active stocks, you will not wait more than few secs to a min, for all 6000 shares to get executed. But in case after buying 1000 shares, the price moves up say back to 1551, you need to wait until it comes back to 1550.
Coming to your second question, if you have executed 6000 shares at 1550, your order is complete and the share price will remain there at 1550, which is the Last Traded Price. If demand is there (if more people are willing to buy) price will tend to move higher say towards 1551. If supply is more (more people willing to sell) the price will tend to come down say towards 1549.
So based on demand and supply, it will either move up or down.
Whether your order will be fulfilled or not depend on how the price moves. if the price is above 1550 through out the day , then your order will not be fulfilled. if the price comes to 1550 and then rise again, your order will be fulfilled (not necessarily complete, it can be partial also). Your order will be completely fulfilled if the price come down below 1550. so a buyer with huge quantity at a price will act as support for that price, which means only after his quantity is exhausted the price will move down. likewise a seller with huge quantity at a given price will act as resistance for that price, so price will rise above that price only after his order is completely fulfilled.