2) Don't take CSGs on a snake map (unless you've got Nomads); one of the AI HWs will always be halfway along the map, and the odds of having all the CSGs you need on "your" half of the snake are pretty slim.
Managing to bypass a core (2 core worlds + 1 home world) would be an interesting challenge, as Valorian_Nova proved it. Or a frustrating one, it depends. It is also possible to play a "two heads snake" game with a 40 or less planets map and picking a home world away from the "head": this way the player ends up with the AI home worlds on each side and all CSG accessible. Could be an interesting thematic game.
1) Everyone loves !Fun!
Sorry for being know-all but this detail matters to me.
If it come from Dwarf Fortress, it's spelled !!fun!! (or !!FUN!!, or !!Fun!!, doesn't matter). DF objects' names are surrounded by symbols to indicate they quality level. For instance, a +diorite table+ is a well made stone table. Objects burning are surrounded by !!, like a !!palm wood chair!!. As fire is part of the failures that are fun, DF community started using !!fun!! to refer to this kind of entertaining failure or difficulty.
But you're right. Everyone playing AI War and DF loves !!Fun!!