English As A Second Language: A Strange Preposition

This is something that's been kicking around my head for awhile. While I was prepared for the different usages that everybody who knows anything about Britain is familiar with (lorry vs. truck, lift vs. elevator, boot vs. trunk), one of the usages that surprised me was the different prepositions. This is, I suppose, just another one of those things that emerges when people speaking a similar language are divided by an ocean for a few centuries. I find myself unable to adjust to these usages in my own speech. For example:

American usage vs. British usage

At 5 p.m. vs. From 5 p.m.
On Fleet Street vs. In Fleet Street
During, over, or this weekend vs. At the weekend
(Not a preposition, but ...)
Take a decision vs. Make a decision
Take exercise vs. uhhhh, exercise

These are hardly a big deal, I suppose, but I can't get used to them, even after two years.