The emulated Spectrum is, by default, an unmodified 48K Spectrum with a tape player and ZX Printer attached. Oh, and apparently some magical snapshot load/save machine which is probably best glossed over for the sake of the analogy. :-)
To emulate different kinds of Spectrum, use the Machines tab on the preferences screen (available from the Fuse, Preferences menu option).
The Spectrum emulation is paused when any dialogs appear.