You are most likely correct here. With IR you would typically need line of sight between the sender and receiver. Having said that, sometimes you can get the signal to reflect on objects to get to the receiver. Your mileage will vary here.
You should only need one instance of the app. Within the app you can add several Bond devices. This is what my Bond app looks like after having adding only one Bond device (bridge):
A cheaper alternative to Bond would be Broadlink. You can get Broadlink mini for around $20 USD from AliExpress. The minis do IR, but if you want RF you need the pro. There is no official support on HE for them but there is community support: Broadlink IR/RF remotes integration (RM3 Mini, RM Pro, RM4 Mini/Pro)
I use a Bond bridge for my 10 motorised blinds in the house and I use two Broadlink minis for two TVs.
