The Gyro aiming is optional and can be turned off if you see fit. As an alternative you can simply use the analogue stick to aim which ever weapon you might be wielding (Its used to aim the slingshot, bow, boom-a-rang, hookshot, etc).
However; as a personal preference I find the gyro-aiming considerably easier and much more responsive to use compared to the stick aiming.
In my experience the Activity Log is inaccurate for DS and DSi titles when you've suspended them across midnight.
When I first got my 3DS, I noticed it discarding any played time before midnight if I suspended it overnight - I'd play a game for an hour before bed, go to sleep, play an hour the next day, then quit and check the Activity Log, and I'd see a single hour played.
Recently, this hasn't happened, but instead I seem to have the entire day counted as one play session even if I took suspend breaks during the course of the day. I cannot say if this changed one of the firmware updates, or if it's just another symptom of the same underlying bug.
I only recall one game that counted suspend time against the in-game timer, Hotel Dusk, in which I racked up about 150 hours of supposed play time. If Activity Log is accurate, it should always be longer than the in-game reported time. It will count time in save menus, option screens, music players, replays if you give up and come back later at an earlier save point, and so on.
Which is more accurate depends on the kind of game, but in general the in-game time is probably more accurate, especially if you are trying to gauge the length of a game.
Best Answer
Yes, Streetpass works in different regions. I personally travel a lot and have streetpass-ed hundreds of people with 3DS from different regions on public transport.
About your second question, it seems that that is not possible due to the servers being different. Source: