Could not reproduce it with the current development version. Please send me feedback if this is still an issue in the next released version.
Please try this in the next snapshot (whichever version we release after 16w06a) and tell us if this is still an issue. We might have found a solution but can't be sure without more testing. So if you have a world that's heavily affected by this issue, your feedback will help us a lot to solve it.
This is explicitly not done for performance reasons.
The fixed behavior is correct. I'm considering to have a new stat for "accidents" (counts how of players kill themselves) some time in the future (after 1.9, not for 1.9)
An idle timeout of 74 days is more than enough, probably longer than the uptime of even the most stable Minecraft servers.
Decimals are not recognized, the selector parameters are all integers. But it should now consistently fail instead of creating a player on the scoreboard with the selector as name.
The content of inventories is not considered tile drops, so this gamerule doesn't apply
Fixed again (for the 3rd time, fixing a 4th bug in addition to the 3 bugs I already found last time), hopefully it's now solved completely.
Use NBT in the summon command to provide some air to the mob. e.g. /summon Pig ~3 ~ ~ {Air:300s}
This issue is fixed for entities saved in 1.8.1 or newer. Loading older worlds can still have some entities with this issue in the world. Simply closing the world and loading it again should automatically solve the issue for those entities.
We can't reproduce this issue with the steps you described. Please provide a world download that reproduces this issue.
Please don't use the bugtracker for feature requests.
Piston extension is an internal technical block and it's not supposed to be used in maps.
This should already be fixed in the most recent snapshots
Fire is a special block type, like water and lava and maybe some that I forgot to mention. They can't be broken by tools with this tag, because that would require special casing the behavior of these blocks.
Fixed for all but the rails.
I'll take a look at it next week.
For now I'm not going to change this behavior because it would cause a performance hit for ALL fill operations. For this special case I recommend a workaround by filling with another block (like stone) first and then with lava.
This is only the case in offline mode servers. We do not support whitelist and banlist in offline mode, because they are pretty much useless without online mode.
If anyone can still reproduce this in the latest snapshot, please send me a copy of the world. I can't reproduce it with any of my test worlds.