设\(n∈N^{*}\),\(n\geqslant 3\),\(k∈N^{*}\).
\((1)\)求值:
\(①kC_{n}^{k}-nC_{n-1}^{k-1}\);
\(②k^{2}C_{n}^{k}-n(n-1)C_{n-2}^{k-2}-nC_{n-1}^{k-1}(k\geqslant 2)\);
\((2)\)化简:\(1^{2}C_{n}^{0}+2^{2}C_{n}^{1}+3^{2}C_{n}^{2}+…+(k+1)^{2}C_{n}^{k}+…+(n+1)^{2}C_{n}^{n}\).