bike lots = win, swim lots = ??

All depends.  If you are a really slow swimmer, time spent in the pool might pay benefits, not only for time but to get you on the bike feeling less tired and fresher.  As your time gets faster, however, more swimming becomes less relevant/not worth the effort

As an example, it if your pace is 1:30 per 100, the energy it takes to get to 1:20 for an Olympic distance is probably not worth the extra effort to get roughly 3 minutes over that distance. 

Swim lots means you come out of the water fresh and ready to take advantage of cycling lots.

For the "don't swim lots, but ride lots" result, see my Eagleman race report from last year.

When I started tri training I literally couldn't swim a full lap in a 25 yard pool. I used the TI book and it helped get me to the point where I could do an open water swim in a half ironman. I was slow in the water and exhausted when I got out but I could do it.

I then did the following:
- invested $100 in 2 lessons with a local TI instructor.
- did the drills exclusively for a couple months
- was lucky enough to have a couple friends who are great swimmers spend some time advising me on my stroke.
- started doing the swim workouts from my training plan as written

This has made all the difference in the world. I'm a decent swimmer now and in my last 2 races I felt really good in the water for the first time and exited it feeling great. You don't necessarily need to get a coach, but a couple lessons from a good instructor or at least someone who already knows how to swim fast and efficiently can only help.

For everyone who posts a question that's been answered before, there are 100 or more people who have the same question. The value isn't in having the same information repeated, it's that for everyone who posts the question there are 100 or more people who are wondering the same thing right then and who get a lot out of realizing that there's someone else, right now, who just like them is wondering about the subject. There's a lot of value in letting people know that they're not alone with what ever it is they're wondering/worrying/freaking out about. It also gives new people the opportunity to answer the question, to pass on their experience. You could probably get the information from a book but you don't get a sense of community from a book.

One of the things that draws me to triathlon is that while it's a solitary sport it's very much a shared experience.

I will share my experience.  When I started if I had to do an olympic swim, I'd make sure with every workout I was swimming 1500-2000 yds straight.  That's how you make sure you can do it, right?

Basically I was slow.

I read a thread on here from a real, expert swimmer, that stated outside of Time Trials or other monthly-type tests, she NEVER did sets of more than 500yds, because she built fatigue, she would grove in poor form habits.  She suggested on that post (assuming you can't get a coach or masters involved) to swim 50s-100s over and over again, practicing different things, like pressing your chest down, splashing the surface a bit with the feet, extending your arm, keeping elbows up, etc. and looking at the feedback in terms of your time.  Try to incorporate different things that worked in terms of time improvement.

That really helped me.  I'm no fish, but I'm more confident and have shave a lot of time off doing that.

How long did the 5K take you? That's a little on the insane side.