OSX App/Strategy for organising my iTunes library for iTunes match?

I have a 200 GB iTunes Library.

Of this 175 GB is Video/Apps and 25 GB is audio(20 GB Music, 5 GB Audiobook, podcasts)

I subscribed to iTunes match. The problem is iTunes match is informing me that it needs to upload about 5 GB of Music to the cloud.

I am pretty sure iTunes has most of the tracks already in its database that it is asking me to upload.

I have come to the conclusion that incorrect meta-tags are the culprit here.

I have 2 questions :-

1)Can someone recommend a software that will autocorrect my music tags(artist, album, track name, composer, genre, year, etc.)??

2) Some of the album art is missing, low-resolution. How do I ensure that the best resolution album art is uploaded to my iTunes match database & also subsequently replaced on my existing local copies on my desktop iTunes app?