If after any letter of Madd, there is a hamzah or sukoon or tashdeed, then this Madd is called Maddul Farie. If after any letter of Madd, there is no hamzah or jazam sukoon or tashdeed, then the letter of Madd will be stretched for one Alif. Qalqalah is a quality, which when pronounced, appears to have an bouncing sound,when the letter is saakin.
These letters are also known as Mufakh'kham letters. Tajweed rules means to recite every letter of the Quran correctly from its makhraj with all of its qualities.