如图,四边形\(ABCD\)是边长为\(1\)的正方形,点\(E\)在\(AD\)边上运动,且不与点\(A\)和点\(D\)重合,连结\(CE\),过点\(C\)作\(CF⊥CE\)交\(AB\)的延长线于点\(F\),\(EF\)交\(BC\)于点\(G\).
\((1)\)求证:\(\triangle CDE\)≌\(\triangle CBF\);
\((2)\)当\(DE= \dfrac {1}{2}\)时,求\(CG\)的长;
\((3)\)连结\(AG\),在点\(E\)运动过程中,四边形\(CEAG\)能否为平行四边形?若能,求出此时\(DE\)的长;若不能,说明理由.