Redefining commands in a new environment

Question

Two questions:

1. Does LaTeX allow one to (re)define commands within a \newenvironment? I've tried using \renewcommand, \newcommand and \def in the before declaration but to no avail.

2. How would one redefine \item when creating a new list environment?

I've created a new type of list environment from scratch using \newenvironment while using another token instead of \item for each but I'd really like to keep things consistent by using \list and redefining \item.

Answer 1

Too late perhaps, but it may be useful for someone else

\newenvironment{coolitemize}{%
\let\olditem\item% 
\renewcommand\item[2][]{\olditem \textbf{##1}\\[0.3\baselineskip]##2}%
\begin{itemize}}{\end{itemize}%
}

and use it

\begin{coolitemize}
\item[Title of my first item] Text of my 1st item.
\item[Second one] And some text here.
\end{coolitemize}