已知数列\(\{a _{n} \}\)、\(\{b _{n} \}\)满足：\(a _{1} = \dfrac {1}{4}\)，\(a _{n} +b _{n} =1\)，\(b _{n+1} = \dfrac {b_{n}}{(1-a_{n})(1+a_{n})}\)．
\((\)Ⅰ\()\)求\(b _{1}\)，\(b _{2}\)，\(b _{3}\)，\(b _{4}\)；
\((\)Ⅱ\()\)设\(C _{n} = \dfrac {1}{b_{n}-1}\)，求证数列\(\{C _{n} \}\)是等差数列，并求\(b _{n}\)的通项公式；
\((\)Ⅲ\()\)设\(S _{n} =a _{1} a _{2} +a _{2} a _{3} +a _{3} a _{4} +…+a _{n} a _{n+1}\)，不等式\(4aS _{n} < b _{n}\)恒成立时，求实数\(a\)的取值范围．