Regarding the planet limit bugs, workarounds, and manthano-3 specifically:
Attacking while at planet limit
Attacking while at planet limit
Planet limits used to only apply to exploring, and not to attacking. This was an oversight as it was initially thought not to be needed in a peaceful galaxy, but intra-fam trades and inactive clearing allowed players to knowingly bypass the limit.
Now, when you win an attack, if you are already at the limit you will receive the following message:
As you have met the planet limit in this galaxy, The Galactic Overseers have deemed this planet re-explorable for other empires.
A similar message will show in family news:
It’s worth noting that you can still attack while at the limit, for fleet runs and such. It is only what happens if you win that is now different.
Exploring with the old map
Exploring with the old map
This one is much simpler; it’s just a fix to the old map to respect the limit.
Current empires over planet limits
Current Empires over planet limits
Planets have been released at random for empires that have gone over the limit, and the galaxy has been restored to its intended state.
There were 6684 planets in possession that shouldn’t have been. This was at the detriment to new people who joined, found no space to expand, and probably left.
Several players have demonstrated/admitted/etc that going above the limit required using known exploits. Nobody will be banned, but for some players that means they just lost hundreds of planets.
This is something I very specifically warned about the last time this situation was addressed:
If you stayed under the limit, thank you for being considerate of new players. 
If you didn’t stay under the limit, losing excess planets was inevitable.
Thanks, and please let me know if you have any questions.