Two 8 ohm speakers in parallel is 4 ohms, and the power will be split between them.
However, unless the amplifier is rated for 4 ohm operation, you will not get the same total power out of the...
Yes, you can connect two 8 ohm speakers to an 8 ohm amplifier, but do not expect full power range. That is not normally a problem, because we rarely, if ever, run an amplifier at anywhere near full...
You can sure, the issue will be the amp driving the speakers, an amp with a low impedance output will be very inefficient with these speakers. So ideally for a effective and efficient system, it's...