Replaygain questions (Winamp + Foobar2000)

[KrustyForum]

I'm new to the use of Replay Gain, and would like to get some info about it.
Right now, I use Foobar2000 to ad the Replay Gain info to mp3 or flac files. And I use WinAmp v.5.21 as my default music-player. I can see on the info, on Flac files, that I have add'ed Track Gain and Album Gain. But I'm not sure weather the default WinAmp v.5.21, without any plugin added, understand and play replaygained files. Or do I need a plugin?

My second question is, does that plugin also writes Replay Gain info into files?

And third: Is there any difference in having Replay Gained your files in Foobar2000, or in WinAmp? (Difference in the files)

And fourth: If a Replay Gained file with both Album and Track Gain info, is played in WinAmp, what info does WinAmp adjust the volume to?

Thanks

KrustyForum