The problem is everyone expects Calc to be Excel, including full compatibility with reading and writing of Excel's file formats. As Excel is a constantly moving target, following that path means you'll forever be a second-rate Excel that'll never quite be fully compatible.
I find Calc to be a fine spreadsheet program myself, though I'm hardly a power user. If you want to use Excel, then just go use Excel.
For clones of WinAmp for Linux, there's qmmp (which I use) and I believe some distros still have an xmms package (xmms2 is a bit of a different beast). xmms hasn't seen an update in a long time but like old versions of WinAmp it still works. Both of them have some support for classic WinAmp skins. Neither one supports the full feature sets of WinAmp such as the media library or video playback, so it depends on what parts of WinAmp you're looking for.
WinAmp also runs under wine and basic stuff works, but last time I tried it I ran into issues with some of the plugins and the basic stuff is covered by qmmp so other than nostalgia reasons I didn't really see much point in running WinAmp under Wine.