i can't answer your questions , but here's a review of it and a quote from it to keep in mind .
Dosy FC50 Frequency Counter Review
"Before we go further I'd like to make an important point. If you are an operator who runs SSB, an external frequency counter is not going to give you a steady frequency readout of where your are transmitting. Because of the way single side band works the frequency display on an external frequency counter will jump around all over the place as you talk and the frequency shown will change with the pitch of your voice. The only way to get a steady reading is with a tone generator which is not what most CB operators would be looking to do. If you are looking for a frequency counter specifically to track your TX location while in a SSB mode you'll need to buy one that can be hard wired (soldered) to the radio. If you have a SSB radio and are using it in AM mode in conjunction with this counter the Dosy FC-50 will work perfectly."