I don't find the screen a problem (Unless you take out in the sunshine

), even with the size it does a good job for gaming, which was one of the worries I had, but as it's not my main gaming rig I could deal with it on the move. The r1 has a better battery life, but is obviously a little bit slower than r2 (There are a few volt mods for the r1 to get it to match the r2, but requires some soldering).
Haven't heard of the 5400, there is the 4100 or the slightly faster 7300. I know with mine (7300), it automatically overclocks to 1.7ghz.
Speakers aren't great, but I'm normally using headphones anyway, so didn't bother me. Both those games should play, a few settings will have to be turned down, but not to the extent you won't enjoy the games. Wow, because it's a CPU intensive game will probably be playable at medium settings, the r2 in this case would be a lot better for it.