CRJ900 First Officer reported incorrectly extending flaps instead of the landing gear as well as encountering issues with the EFB software making checklist usage difficult. Corrections were made to the aircraft's configuration prior to 1;000 ft. and a normal landing was completed.

Narrative

On approach to landing; pilot flying called for gear down. I hit chime and inadvertently selected flaps 30 and read off flaps 30 straight-in speed. Pilot flying then called for flaps 30 and I noted we were flaps 30 and again straight-in speed. We both expressed confusion as why I had already input flaps 30. Then; Captain called for check spoilers; flaps 45; before landing check." I checked spoilers 0; flaps 45; straight-in speed; and went to read the checklist and [my EFB] crashed. I attempted to restart and then did checklist from memory because it was taking a long [time] to reload. I correctly called the checklist; but we did not identify that the gear was still up. The gear warning subsequently sounded. We corrected and landed. This happened at the final approach fix; although we were visual.Possible causes could be my lack of good rest for the entire trip. Day 1 was extended and we received less than 12 hours between airport to airport. Day 2 was minimum rest airport to airport. Day 3 ended with adequate rest opportunity but I didn't sleep well due to getting up at XA:00. Also; this was the first trip I was using [the EFB software] for checklists and it hung multiple times when attempting to use the checklist. This caused more rushing and distraction when checklists were called for and being read. I was expecting gear down callout and ready for it. Possibly unrecognized fatigue caused me to go for the wrong control.Resting better would have helped avoid this event. I will no longer use [the EFB software] for checklists until it is more stable. We could have gone around; but there is some ambiguity in the decision process for going around. We recognized the error and corrected; returning to stable approach before 1;000 ft. HAT on a visual approach."