Concrete Countertop

Love these, have always wanted to do one. Fu-Tung Cheng article in FHB 146, May 2002 has inspired me.  Will start with my own.  Lady asked me many years ago but I said no because of my lack of experience and information at the time.

Fu-Tung Cheng put a split in the middle of the sink, for weight and for shrinkage. Isn’t that a major stress point and area to worry about water? I take it he epoxied the joint.  Would like your opinion.

I have built the cabinets real flat and sturdy.  However, isn’t there something that should be put down to give the top support if something is slightly uneven; liquid nails, silicone, mirror mastic?  Something that would squish in the tight spots and support if there is a little gap.  Or am I being paranoid?  I know the weight will keep it in one place.

I also want to cast separately a back splash, for this can I go as thin as 1 1/4″?

The counter will be 23″ by 8 foot long with a sink just off center.

Thanks.