I dont think it is inside the faq so I'll answer your enquirers from my personal experience.

1) Latency wise, you will have barely noticeable 300~400ms delay to play on US server.
2) Looking for a quick match on SEA could be a pain. As there are currently only about 2000 games online at any time. It had indicated only 2000 to 4000 concurrent players at maximum (for a title like SC2, it is considered very low players count). Many custom maps creator have no intention to publish their maps in SEA Battle.net. The only advantage you will get to play on SEA is the network latency.