Testforblock can't detect signs with a '=' in them

Mouse Drift

When I add a resource pack to a world (using Resources.zip) it successfully loads, but there's a resource pack called "Server". It has a missing texture as a picture.

A jukebox summoned by a command block won't play any music. If you put the record in by hand everything works perfectly fine, but if you try to recreate that with a command block the game doesn't play the music.

I can't launch versions above 1.8.3

/blockdata ~ ~ ~ {Items:[{Slot:0b,id:minecraft:air}]} Deletes every item. I used this command In a Furnace to delete one slot but all the other slots get cleared too.