Get the tracking checked and also check your pressures. I don't think a 4 wheel alignment is worth it unless your rear tyres are wearing unevenly too and I don't know how much adjustment a Focus provides for anyway.
For future reference - if you look in the deep treads you'll find several raised points (in your last pic there one just below the stone thats stuck in the tread). these indicate the legal minimum tread level. That said its not always a good plan to run down to the minimum.
As others have said tyres are not in great shape and it certainly looks like there is an alignment issue which you shoudl get checked as otherwise you risk have the same issue on the new ones when they are fitted. Also will be causing you to have less than maximum grip etc.
The legal limit for minimum depth of the tread on your tyres is 1.6 millimetres, across the central ¾ of the tread around the complete circumference of the tyre.
I would think those have been under inflated to wear out the edges like that. I would change them asap as they must be close to 1.6mm across 75% of the tread and in that condition they are not going to move much water in a heavy shower.