Ah, yes, east, west, left, right... I always get that wrong... 
Or as we used to say as kids: "Go left". Friend goes left. "No, no, I mean 'the other left'!"
In any case, you are right: pushing that city further east makes sense only if there is indeed flat land again on the other side of the hill range.
As to the 3SW site: an extra irrigation is not much effort, we'll need tons of workers anyway. An optimal city site for the rest of the game is a much more important factor. And having 2-3 additional coast tiles that can be worked for the rest of the game is a lot. Also consider: the sugar tile can be accessed from 4SW as well, so that wouldn't be a factor.
But in any case: all these locations are still question marks, we cannot decide them yet with the current information we have. For example, if a whale or fish becomes visible that can be accessed only from 4SW, then the decision becomes a no-brainer anyway...

Or as we used to say as kids: "Go left". Friend goes left. "No, no, I mean 'the other left'!"
In any case, you are right: pushing that city further east makes sense only if there is indeed flat land again on the other side of the hill range.
As to the 3SW site: an extra irrigation is not much effort, we'll need tons of workers anyway. An optimal city site for the rest of the game is a much more important factor. And having 2-3 additional coast tiles that can be worked for the rest of the game is a lot. Also consider: the sugar tile can be accessed from 4SW as well, so that wouldn't be a factor.
But in any case: all these locations are still question marks, we cannot decide them yet with the current information we have. For example, if a whale or fish becomes visible that can be accessed only from 4SW, then the decision becomes a no-brainer anyway...
Can we actually settle on swamp in Conquests, or does it have to be cleared first (told you, I'm a n00b!)?

Let's go and get it!
)

). Unfortunately they know BW and WC. But I'm able to buy Alphabet for Pottery, 11g and 7gpt. Stiff price, we can't accept that, it would keep us from doing any research! (The extra worker will soon cost -1gpt.) So I sell them pottery for 10g. They go from annoyed to cautious.
In the hands of a human player, that tile would be a horrible weapon...