[Ogedei]

I'm a bad person in some ways when it comes to this.

When I have the lane, I swim close to the middle.
I suck at swimming on the side of the lane. I am super paranoid about taking up more than my half so I tend to hug the ropes a little bit, ie run into them, which takes pretty much all the fun out of it for me.

So when I don't have to swim along the edge I don't.

In terms of politness. I can't imagine starting in a lane without the other guy knowing you are there.

I had one guy just recently get into the lane I was using and start swimming his first 25 when I was coming back. As I mentioned I don't tend to swim along the edge, and I had no clue he was in the lane. Bad Idea.

So in my books, if the lane is there, swim it however you want. Be aware of new people who have gotten in when you get to the entry point, and above all don't start swimming until the other guy in the lane knows you are there.

That's my 2 cents.