Are you within range of a LoRaWAN Gateway, or are you thinking of adding your own ?
It does but it doesn’t do sleep out of the box. And as above, you can barely fit any other libraries in.
Technically I believe yes, but as noted I wouldnt go for that these days given its constraints and limitations! 
Devboards with externa(SPI) LoRa Module or better yet the full list on the original github link…
Are there a table available as to compare Board to sleep current and memory?
Did you look
So unlikely.
As for memory, pretty much everything apart from the ATmega328/32U4 has plenty and they have not enough.
No my 
, it is broken 
Well volunteered …