I'll just state what I know from experience. I have a Japanese PS3 but I have all the language settings set to English. I use 2 different PSN accounts one is a US account the other is JP. I primarily use the US account.
For Resistance, even if I use my US PSN account, and all my configuration for region is set to English, still in multiplayer it still only connects to JP servers and even the legal disclaimer message and server notification will be in Japanese.
But thats probably because Resistance does not really use your PSN account. The gamer ID is the same, but it uses a totally different system for messaging buddy lists etc.
Ridge Racer 7 is intentionally global. So no problem there.
For a downloadable game like GT:HD it is totally is dependent on what PSN store you downloaded it from. If it was the JP store, the online scoreboards are region specific and the menu interface is Japanese.
My credit card is not valid in the US so I can only buy from the JP PSN store at this time. The few games I have bought from it (Tekken, Lemmings) are fully Japanese in their interface. I really want FlOw - but it's not on the JP store yet.
As for download speeds from the PSN Store. It's almost always fast for me regardless of what PSN store I download from. I thought it would be significantly slower from the the US store, but it has been quite fast for me. Only on some bad days it feels a bit slow. But there is no actual download speed indication with the current version of the firmware. So how "fast" the download is, is just a gut feeling for now.
