You have to fill the following fields for all the files that should belong to one album:
ALBUMARTIST
ALBUM
YEAR
Each field should be filled with the same contents as the corresponding field of the other tracks.
It is not necessary to have the same cover in each file - but it is up to the player whether he shows just one for all or the separate ones.
There are actions to copy the contents of one field to another, e.g. if you want to keep singles as singles then you can easily copy the contents of TITLE to ALBUM.
The same applies to ARTIST and ALBUMARTIST.
Unless you have a separate copy of your collection to synchronize with the mobile player, I would not mess around with the already distinguished data only to make it look nice on a player. Once you have lost information (which you do if you replace the differentiated info with the same for all), it is hard to get it back.