Hi, The Overground trains are very crowded in the morning rush hour, I recommend the front carriage. And I'd go for a little earlier than 8am if you want space. Trains to London Bridge in rush hour are less crowded (certainly compared to pre Overground). But then the Southern Rail trains have more carriages than the Overground!

Not had any problems at HOP station re safety over the past 3 years. Since the Overground came in at least the station is manned. Probably the biggest failing at HOP is that it is only stair access, no lifts, not good if you have heavy luggage / prams.