Find only one different extension, whole path, last write time, only files and over 260

Hello!

I need some help with my PowerShell script. This is what I got so far.

Get-ChildItem p:\ -Include *.* -Recurse | Where { ! $_.PSIsContainer } | Select-Object Extension,LastWriteTime | Sort-Object -Property Extension -Unique | Out-File c:\skriptit\file.txt

I need to find out every different extension what there is our shared files. I want only one file for each extension and it have to be last time when somebody used(write) it. I also need whole path and over 260 character
long. Also every subfolders and only files, no folders.

This script what I have, it take first extension it finds and take that Last Write Time. Also threre is no full path and no over 260 characters.

Mika