Homeworld Invasion Defense Rebalance Needed

Several games I've played have ended very badly thanks to a desperately needed rebalance issue.  Somewhere between turns 45 and 65, a faction declares war on me.  A small number of turns later, it's game over.  Out of nowhere, a troop ship hits my homeworld and captures it.  I have the homeworld ringed with starbases, so my vision goes a good way out.  I have a defense rating on the homeworld that is at least 50 percent higher than any other homeworld.  I used to think the range of a ship is such that they can come from beyond sensor range and knock out my homeworld, taking 75 percent of my empire's production, but with the ring of visibility from the starbases I have, this shouldn't happen.  It is very frustrating.

Other games when a world is attacked, I get a symbol that the colony or core world is under invasion and I have x number of turns to disrupt the invasion.  But not here.  Not my homeworld.  This is a game ender and a bad mechanic.  It's twice as bad because of the notification that other colonies and core worlds get, but not the homeworld shortly after the first war declaration.  

In general, one of the things I must constantly do is look for enemy ships in my territory every turn.  It would be a good feature to add a circle or a colored hex around an enemy ship so that when you look at the map farther out, you'll instantly know where the enemies are in or outside of your territory.  I am constantly having to click fleets to see if they're friend or foe when at war.  This is a tedious mechanic.  Presumably, a fix here would fix the first attack game ender above.

Thank you for your consideration on this issue.