Please file this as a feature request ("Please add OPML file import to gPodder") at https://bugs.maemo.org/enter_bug.cgi?product=gPodder

In the mean time, the workaround is as follows:

• Save the file to the data folder of your N900 (so that it appears in the file list that appears when clicking on your device in the file manager, or /home/user/MyDocs in "technical terms")
• Start gPodder and click on the "Subscribe" button
• Click on "OPML file from the web"
• Enter "file:///home/user/MyDocs/filename.opml" (where filename.opml is the name of your OPML file)
• You should now see the feeds from your OPML file - pick the ones you want to add to gPodder

(The feature request that you are hopefully going to file is for another button "OPML file on my device" that will utilize a proper file chooser instead of having you enter the file:// URL.)

The built-in media player does not do that for audio files (bug 1129), although it does it for video files.

Panucci does that, but it is currently not selectable from within gPodder (this is already filed as bug 6325 - feel free to subscribe to it) - in a future version, you will be able to choose between Media Player and Panucci for playing audio files in gPodder, and when selecting Panucci, it will remember the playback position of the podcast.

The workaround here is to install Panucci and manually open files from the "Podcasts" folder where the files are downloaded.