如图,已知直线\(l_{1}\):\(y=2x+m(m < 0)\)与抛物线\(C_{1}\):\(y=ax^{2}(a > 0)\)和圆\(C_{2}\):\(x^{2}+(y+1)^{2}=5\)都相切,\(F\)是\(C_{1}\)的焦点.
\((1)\)求\(m\)与\(a\)的值;
\((2)\)设\(A\)是\(C_{1}\)上的一动点,以\(A\)为切点作抛物线\(C_{1}\)的切线\(l\),直线\(l\)交\(y\)轴于点\(B\),以\(FA\),\(FB\)为邻边作平行四边形\(FAMB\),证明:点\(M\)在一条定直线上;
\((3)\)在\((2)\)的条件下,记点\(M\)所在的定直线为\(l_{2}\),直线\(l_{2}\)与\(y\)轴交点为\(N\),连接\(MF\)交抛物线\(C_{1}\)于\(P\),\(Q\)两点,求\(\triangle NPQ\)的面积\(S\)的取值范围.