Wav files can be compressed, but generally are not, so if you burnt a CD with uncompressed WAV files on it at the same sample rate and bit rate as an audio CD (basically the same quality) then yes, the WAV files would take up about the same amount of space as raw audio files. (the may be minor differences due to differing overheads)
Some CD players would play them, some wouldn't, some might depending on such things as file name lengths, folder structures etc, there is no common standard for that sort of thing.
However, you'd get no benefit from turning a MP3 into a WAV to put it on CD, doing so wouldn't add quality to the audio that wasn't already there.
If you want to put your MP3s onto a CD so any CD player can play them then your best bet by a long way is to use something like windows media player, or nero burning rom (or loads of other burning programs) to actually burn the CD as a proper audio CD rather than a computer CD with audio files on it.