(1) Since the sequence $\{a\_n\}$ satisfies: $a\_1a\_2…a\_n=1-a\_n$, $n∈N^{*}$.
When $n=1$, $a\_1=1-a\_1$, solving for $a\_1$ gives $a\_1= \frac {1}{2}$.
When $n≥slant 2$, $a\_1a\_2…a\_{n-1}=1-a\_{n-1}$, thus $a\_n= \frac {1-a\_n}{1-a\_{n-1}}$,
which can be rewritten as: $\frac {1}{1-a\_n} - \frac {1}{1-a\_{n-1}} = 1$,
Hence, $\{ \frac {1}{1-a\_n} \}$ is an arithmetic sequence with the first term $2$ and common difference $1$.
Therefore, $\frac {1}{1-a\_n} = 2+(n-1)=n+1$.
Solving for $a\_n$ gives $a\_n = \boxed{\frac {n}{n+1}}$.

(2) Given $T\_n= \begin{cases} 1(n=1) \\ a\_1a\_2…a\_{n-1}(n≥slant 2) \end{cases}(n∈N^{*})$,
When $n=1$, $T\_1=1$.
When $n≥slant 2$, $T\_n=a\_1a\_2…a\_{n-1}=1-a\_{n-1}=1- \frac {n-1}{n}= \frac {1}{n}$,
Thus, $S\_n=T\_1+T\_2+…+T\_n=1+ \frac {1}{2}+ \frac {1}{3}+…+ \frac {1}{n}$.
Hence, $S\_{2n}-S\_n= \frac {1}{n+1}+ \frac {1}{n+2}+…+ \frac {1}{n+n}≥slant \frac {n}{n+n}= \frac {1}{2}$.
The left side of the inequality $\boxed{\frac {1}{2}≤slant S\_{2n}-S\_n}$ holds.
Since $S\_{2n}-S\_n= \frac {1}{2}[( \frac {1}{n+1}+ \frac {1}{n+n})+( \frac {1}{n+2}+ \frac {1}{n+n-1})+…+( \frac {1}{n+n}+ \frac {1}{n+1})]$
$< \frac {1}{2}( \frac {3}{2n}+ \frac {3}{2n}+…+ \frac {3}{2n})= \frac {3n}{4n}= \frac {3}{4}$.
The right side of the inequality $\boxed{S\_{2n}-S\_n < \frac {3}{4}}$ holds.

In conclusion, $\boxed{\frac {1}{2}≤slant S\_{2n}-S\_n < \frac {3}{4}}$.