I would expect schematics etc to be available when the board ships. This is how it worked with previous boards. Perhaps because until then, we can’t be sure that the current design is the final design.
I have no idea if the FU740 will be sold separately. We never sold the FU540 separately. Keep in mind that SiFive is not a computer company or a chip company. We are an IP Core company, like ARM. If you want to buy an ARM chip, you don’t buy it from ARM, you buy it from an ARM customer. Simarly, if you want to buy a SiFive chip, you shouldn’t expect to buy it from us, you should expect to buy it from a customer of ours. Unfortunately the market isn’t quite there yet. I know that Microchip is selling the chip used in the Icicle kit which is similar to the FU540, but I seriously doubt that you can buy them one at a time. They are probably only selling to corporate customers at this time. It may be a few years before Linux capable RISC-V chips are commodity parts that you can easily purchase in small quantities.