I havent uad a chance to play the beta yet just the alpha just for a heads up
1) atm minable resources ( antimatter , elerium , etc) allow you to build special weapons modules for your ships granting you bonus range at the cost of damage
however much of the combat has not been implemented yet so its not really noticable. The devs hae said it will have other uses later on as well.
further they dont need to be built on the resource only in range which i believ is 5 hexes
2) this depends on the size of map your playing on a small imo i would probobly rush weapons and planetery invasion
on midsize maps i would focus on growth to get an edge
on large maps i would probobly focus research
3) lower class worlds ~<6 i tend to generalize make them high pop so they can do anything( im not sure how that works with the new approval system)
anything higher than that i would specialize
Im not sure what you mean by polycast broadcasts but there is an archive of dev streams from the alpha and beta you can see them all except for the lost episode