hmm,somebody tell me why I received such a reward? why this is a 5 coin,instead of the usual 2,5   

Could be because you minted this block and the one 500 blocks ago. Since you share the reward with whoever minted the one 500 blocks ago, you would collect both rewards at the same time (plus another 2.5 in 500 blocks of course).

how do I buy this token, I see that many sell only P2P, is there any exchange for purchase?

There is no exchange at the moment but the team are doing a crowdfund to raise money to get the Siriux token list on Cryptopia. Right now the only way to buy or sell your tokens is OTC, you can check out this thread for more information. https://bt.irlbtc.com/view/2687228.180

The price of 5000 SRX tokens is around 0.5 ETH I think, but you need to be careful because there are many scammers here. Try to find a good escrow before doing your trade.

lot of airdrop participant who sell in this thread. better buyers buy through dev so dev can raise funds to pay the listing fee exchange rather than buying from participant airdrop because it will delay this project listed on exchange

Wait for their Further announcement regarding the crowdfunding event for SIRX exchange listing. The fastest way to get an answer is by joining on their slack channel and asking the slack admin about the donation event.

hi,dear dev team. I am quite new to the cryptocurrency and introduced the Sirius by my friend. I really want to take part in this project . So could you please tell me how to get the Sirius coins?  BTT forum is only JR level, can I stand the chance?

hey bro you can get siriux token by donating to the team during the crowdsale but wait for more information on it. The first stage distribution for SR member is already over but in the next month maybe you will be able to join the airdrop and there will have a bounty program like if you work for them you can get Siriux tokens in return. Join their slack if you want to ask them any question or if you need more info.

No information regarding that yet but rest assured we will be able to see more about it maybe before this month ends

I think 1 SIRX is 1200 sats though crowdsale and the min is 0.2 BTC
Crowdsale is first come first served till target is reached