Yes you can run both at once. I assume they are both 2.4 GHz? You will want them to be on separate channels from each other. Preferably either channel 1, 6 or 11. You can use the same SSID on both or a different one. This would work better than using it in repeater mode.
Yes it should come with instructions on how to first set it up and get into the configuration screen. One thing I forgot to mention is in the 2.4ghz band you really want to set your channel width to 20mhz (not auto or 40mhz). This is because 40mhz uses 2 channels. With really only 3 available non overlapping channels, you would be "stepping on yourself" if you were to use 40mhz wide channels on both radios. This would result in slower speeds than 20mhz. Even if you only have one radio in use in a house, I usually advise against using 40mhz channels unless you live way out in the countryside by yourself with no neighbors near that could be using Wifi.
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