Mahjong Street Cafe is a triple-match tile game rather than traditional mahjong: you tap food tiles to move them into a tray that holds seven, and any three of a kind in there disappear.
The seven-slot limit is the whole game. Fill it without completing a set and you lose, so each tap is a bet that you'll find the other two.
It's triple-match: you move tiles into a seven-slot tray and any three matching tiles there clear, rather than pairing free tiles on the board.
By filling all seven tray slots without completing a set of three. Keeping a buffer of free slots is the main defence.
Yes — tap to collect tiles. Nothing to install.