Ah, you are correct… then yes, sata to mobo, with something to secure that cable very well.

1.) Yes, SATA to eSATA will work.

2.) It is not worth it, for stability. Having a cable from mobo to something outside case is unsafe at minimum.

I would go with the other recommendation: get a cheap pci sata/esata card. Cost is small, safety and reliability goes way up, no more kludge adapter going to inside of case.