Need help identifying Neo Geo MVS modifications

Hey all. I recently got a MV4F board through a trade. I was told it was a working board but I saw issues soon as I got it.
So far ive done the battery mod with a non-rechargable cell, removing the 470ohm resistor.

Then I saw a 150ohm resistor blown in half and replaced that.

Now in the imgur link below will be some work that someone at some point did.

There's some chip that has been added on the underside of the board.

There's a bridge made between a ls245 and some blue component.

And lastly someone's cut a trace to a 24mhz crystal.

Are any of these things an issue? Please let me know. Thanks!

http://imgur.com/a/Athvj