We've already discussed it a little on the Discord channel and it looks like there are three mods of appearing on the battlefield:
1) Paradropping. It means appearing on random tiles, not under a roof.
2) Infiltration. (In the sense of tabletop strategy games - using teleports, hidden underground tunnels, whatever; it deosn't matter.) It also means appearing on random tiles, but nodes can be used.
3) Reinforcements. Appearing at a given coordinates, which usually means at the edge of the map. (Would probably require allowing many entry points, so they it is chosen randomly.) Reinforcements should probably arrive together, more or less in the same place.