What is the method for determining the winner in the lottery. And is there any limitation for the participants to participate their entry since the prize pool are cap to 0.5BTC??
I think every answer to your question can be seen in the Home and Lottery tab on the spreadsheet.
After the giveaway ends, 3 bet will be made with the seed shown in the spreadsheet, and numbers will be derived from that like in the example in the spreadsheet.
Bets:
87.78
24.35
65.42
would mean lottery: 8,2,7
ALL 3 NUMBERS MATCH 60%
ANY 2 NUMBERS MATCH 30%
ANY 1 NUMBER MATCHES 10%
NO NUMBER MATCHES 0%
If no one has 3 match, then the pool of that goes to the 2 match, and will be split amongst the winner tickets.
For example: there are 6 tickets with 2 matches, and no tickets with 3 match, then (60%+30%)/6 would be the prize for one ticket with 2 matches. If those 6 tickets are from one user, then he gets all of it. If 6 user has 1-1 tickets then 6 user will get it and so on. Please read the lottery tab carefully, it should be clear from that.
Limitation as you can see, is the 0.5 BTC: "Every 1 participant adds 0.0005 BTC to the Lottery Prize Pool." And you can have one ticket per every 25 points, that is the only limit.