如图\(1\),在平面直角坐标系中,\(O\)为坐标原点,点\(A\)的坐标为\((-8,0)\),直线\(BC\)经过点\(B(-8,6)\),\(C(0,6)\),将四边形\(OABC\)绕点\(O\)按顺时针方向旋转\(α\)度得到四边形\(OA′B′C′\),此时直线\(OA′\)、\(B′C′\)分别与直线\(BC\)相交于\(P\)、\(Q\).
\((1)\)四边形\(OA′B′C′\)的形状是 ______ ,当\(α=90^{\circ}\)时,\( \dfrac {BP}{BQ}\)的值是 ______ ;
\((2)①\)如图\(2\),当四边形\(OA′B′C′\)的顶点\(B′\)落在\(y\)轴正半轴上时,求\( \dfrac {BP}{BQ}\)的值;
\(②\)如图\(3\),当四边形\(OA′B′C′\)的顶点\(B′\)落在直线\(BC\)上时,求\(\triangle OPB′\)的面积;
\((3)\)在四边形\(OABC\)旋转过程中,当\(0^{\circ} < α\leqslant 180^{\circ}\)时,是否存在这样的点\(P\)和点\(Q\),使\(BP= \dfrac {1}{2}BQ\)?若存在,请直接写出点\(P\)的坐标;若不存在,请说明理由.