Will the included shelves support a 2U server, until I get raisl for it?

The product includes 2 fixed vented shelves which should be suitable for supporting equipment temporarily, including a 2U server.

Will the included shelves support a 2U server, until I get rails for it?

The product includes 2 fixed vented shelves, which should be able to support a 2U server until you get rails for it.

Yes. You install them at the height you prefer or you can leave them out altogether.

double click image to zoom in

Sysracks 18U 450mm Wall Mount Network IT Server Cabinet Enclosure Rack Equipped FREE! 2 Shelves, Cooling Fan, 8-way PDU, Wheels & more