I saw this auction and the rules are very strictly which means that the coins will be sold only to one buyer so these will be send to only one bitcoin addresses and the minimum deposit is 100k USD, I think the price will decreased a bit if the winner decide to sell a part of them.

I don't recall anything changing much with previous auctions... So I don't think anything will change now especially because these auctions aren't novelty anymore.

This is not the first time and will most likely be a closed dooor auction. The price of the coins will never be known. Therefore, there will not be any changes in price just like before.

all these auctions have always created some sort of panic among bitcoin users who fear for the bitcoin price but i have never seen a big decline only because of the auction because the auction winner (buyer) is not going to buy that much bitcoin just to dump it the next day and take his money back. because what is the point of that!!

A price decrease is more what I except. Usually they make the price go high to sell the coins that are not at all their at an higher price and it crashs soon.

i do not think there will be a big price movement at all. consider this: the market cap is around 9 billion dollars and we talk about 1.6 million. so the market cap is about 5000 times as big.
if you had 100 bucks. would you really be concerned about 2 cents? 

It just depends on the price these coins are being auctioned for. If these coins get auctioned at the current market rate, then the person in question will most likely keep holding them. If that person gets a significant discount (which is highly unlikely), then that person can choose to dump his coins. But then again, the market can swallow these coins without much problems. Yes, it may let the price drop a bit, but nothing significant. It's not that we are talking about 20,000BTC. That would be a completely different situation where the impact would definitely be much worse.

Yeah i seen this too and there is some strange and strict rules imposed on the bidders.

Why would they only want to send the coins to one address and only within one block, is this a normal type of request for auctioned coins or is there another reason behind it?
Can it be a multi sig address?

The $1.6 million worth of bitcoin is too small to affect the bitcoin price. Even the Poloniex has more trading volume.