I don't come from the stackflow community and I have noticed that some of the etiquette and use patterns from that site have transfered over. Is there a question in one of the many meta sites that goes over these things? For example:
I expected the tools section to be about helping organize the site, but I don't quite see what to do to help.
Having worked on the wikipedia, my tendency would be to organize the many answers into a few, but that seems a no-no here.
I sometimes post from a mobile device, realize later that answer was like the others but still gathered votes. I feel I should delete my answer as I was not first.
I use them often enough that I only ever use the 2day view of things. My usual routine is typically to check the following:
most edited - I look for items with an explosion of edits, something significantly out of the ordinary 2-4. This indicates an edit war, and would need to be looked into, and potentially commented on/flaggd. (we haven't had one of these yet thankfully)
most commented - I check this for abnormally high numbers too. It would possibly indicate an epic debate, or a huge meta discussion.
lowest voted questions/answers - I just check to see why some things are going negative. I may or may not add my vote as well, in either direction.
close - I check this often for things needing to be closed. I don't hesitate usually to nudge them along if I agree with the closure reasons. The recently closed list is important too. Anything closed longer than 2 days should be looked at. If someone has significantly altered the question so that it is now acceptable, then I'll vote to reopen (uncommon), otherwise it's important to vote to delete these to keep the system free of crap. Closed questions still show up in related links and on the main pages.
delete - I use this similar to the close tab, just to see what else needs my vote. These are generally a no-brainer.
flag - This is the most important tab. Thankfully, we've had very few of these. This is where stuff flagged spam, offensive, and moderator attention end up. It's important to act on these quickly when they occur (and are legitimate). This is the only thing that actually will show up no matter what page you're on, there will be a number next to your [tools] menu.
As best I can tell, the 'tools' section are just various reports.
As for merging answers -- I believe it's more acceptable on community-wiki questions (or answers, as it can be done individually).
As for 'similar' issues -- I've done the same thing myself; although answers might be similar, there might be info in the later responses that isn't in the original. When I know there's already an older post, I'll just add the extra bit as a comment to the original. I don't recall what I've done in that specific case of not seeing the 'new answers' message when posting, though.