1. If the external antenna connects to all three antenna jacks on the router and the antenna is outside, will that hurt the wifi signal inside the pole building?
Can effect internal WiFi inside the building if the antenna is placed out side. Signal should be good if the inside area is small or you place the receiving antennae close to where devices are connecting inside the building
2. If I have the external antenna connected to all 3 jacks, will I need 3 external antennas? Or is there an adapter available to hook one antenna into all 3 jacks? Will using an adapter like that accomplish the objective of hooking into all 3?
If the single antenna does not have connectors for all 3, then you'll need 3 separate antennae. I do know of one person who did this with a similar router and bought 3 antennae.
Unfortunately, running a LAN wired cable is not an option, we would have to bust up concrete to go under ground and he doesn't want anything strung overhead.
The home is within line of sight, although a large pine tree and a detached garage is between the two buildings. I'm not familiar with a 5ghz bridge, is that a system that has an antenna on the shop beaming the signal to an antenna on the home that is connected to a seperate router in the house?
Kind of, it would mean placing of one 5Ghz radio or device at one location and a 2nd device at the other location. If there is structures in between then this can effect the signal between. I was hoping there would not be any obstructions in between.
I don't think they have much hope of streaming from the internet, the slow ISP speed is killing that. But they would like to stream a movie pre-downloaded to their computer or ipad to their TV via Google Chromecast. The ISP speed shouldn't affect that, right?
Yes, if you have locally stored files someplace then yes, streaming should work well if you can get the main host Wifi and the remote location WiFi set up well.