Responding to your concerns in order:
1) Is due to a policy Google Checkout enforces for all checkouts placed from mobile devices such as smartphones and the iPad; this does not affect orders placed from a regular computer. Yeah, we think it's a pretty strange and arbitrary policy, too.
2) & 3) Sound like just a temporary connectivity issue or network routing glitch from your location at that time, the same way a Web site might seem briefly slow to load or nonresponsive for one person at times when it loads up just fine for everyone else. That's just the nature of "traffic jams" on the Internet as they come and go.