I'll give this a good read later, good night.
lol who are you correcting? THEN is the proper word to use. THAN would be used in a comparison.
Nope. In all three cases where "then" has been used in the OP, "than" was the correct word to use. It's one of those errors which drives me nuts, too, because those words don't even sound the same so it's hard to understand how you can confuse them when writing (at least brain-farts over two, too, and to are understandable). However, it doesn't detract from the substance of the post so I'm not sure why it was worth mentioning.
You do have me, I am bad at grammer. I'm a native speaker but have spent more then the past decade with non-native speakers. I'll fix it later. Sorry!