Four clubs are chosen each year.
No, the league cup is only for teams in League 2 and above.
It is determined by the teams strength in the Champions League. The stronger the league, the more teams that can qualify from it. The winner of the UEFA cup from the previous year gets an automatic qualification.
I pretty sure the Buffalo Sabres haven't won a Cup... They entered the league in the same year as the Canucks...
There are 16-32 teams in a Spanish Cup
All teams in the Premier League play 38 league games. 19 at home, and 19 away. They all also take part in the yearly FA Cup competition and the League Cup. Some teams play in either the Champions League or the Europa League depending on their previous year qualification and finish.
If the question is, "How many times did the same two teams appear in the Grey Cup two years in a row?" the answer is, lots. In some cases the same teams were in the Grey Cup for three years running, which I would count as two rematches, that is, two games where the teams were the same teams as the year before. So, how many times has the Grey Cup been between the same two teams who were in it the year before? Over 101 Grey Cup games, 16 times, most recently in 2009-2010.