From the DM's perspective, it mostly comes down to obfuscation and training your player base. Don't force your players to resist metagaming if you can reasonably help it.
Going down your list with some concrete examples:
Make truly trivial random encounters a regular (but not necessarily frequent) occurrence. If every encounter is non-trivial, then a trivial one will scream "ambush."
Again, if you use minis to represent statuary on a regular basis, it will stick out much less.
Don't bring the map out until it's actually needed (combat starts, the players need more detail to search). If for some reason you need the map before the PCs realize what's going on, find some pretext for using the map tangential to your actual purpose. In addition, if the PCs start doing more than passive information-gathering, ask them why their characters are suddenly acting the way they are.
Don't use public rolls for knowledge checks if misinformation is a possibility. Realistically roleplaying belief in something you know to be untrue is extremely difficult. Alternatively, instead of giving misinformation, give accurate but incomplete information. In this way the players can rely on what they know, but are left to speculate on what's been left out.
Obfuscation and training will slowly help train your players to metagame a bit less. You can help the process along a bit by explaining things... Talk about how you want to add trivial encounters to make them feel powerful, or minis to help make the map feel more three dimensional.
The trick with talking though, is to be honest. If you talk up trivial encounters and then slam them with an ambush, the explanation becomes part of the metagame.