You can already achieve (1). In the 'tree' view, right click on an artist, go to 'Artist Profile' and click. This brings up a dialogue box with a number of tabs. These include 'Biography', and 'Notes'. You can put all the common info you want in these fields. When you subsequently bring up an album by a particular artist in 'album' view, simply right click anywhere on the album page and select the option 'Artist Profile'. Voila!

Regarding (2), you could use the 'sub genre' field, for instance (well, any field, really) to enter the 'linking' data (let's say GENESIS). Then run a search that looks for GENESIS. This will return all albums with GENESIS in the chosen field. A good field to use might be 'Key words' in the 'notes' section of album properties.

Hope this helps.