So you had a couple of questions there and I will try to answer them as best as I can.
1. Should you put solder on the end of the wire before connecting to the banana plugs? From my schooling and experience as an electrical engineer, you want to make sure that you provide the best connection with the least amount of resistance and also provide impedance matching on any transmission line. While simply adding solder to the end of the wire may help as you might get more surface area contact to the banana plug, it does depend on how you solder it. The best solution, which I'm not going to suggest in case you ruin your banana plugs and blame me :), is to solder the wire right onto the banana plug if that is possible in your case. However, again, it all goes back to impedance matching again, which you will probably throw off slightly. Impedance matching is the matching of impedances (or a resistance to the flow of electrical signal) so that there is no reflection back of any signals. Think of sending water down a big 10" pipe only to get to the end where there is a 5" outlet. Not all the water will get through and some will splash back into the oncoming flow and thus reduce the amount of water that gets out. That's the simplest I can explain it and I hope you get the idea.
2. So you're also asking about matching speaker wire length. Well, it depends. On what? Well, it depends on your receiver really. Some of the new receivers these days have a self calibration feature that measures the distances from listener and thus calibrates when to send the signal through a speaker wire relative to the other speaker wires. If you have one of these receivers, then you really don't need to worry about this. Or perhaps it's not self-calibrating but allows for manual entry, then you can take care of it that way. But again, from an electrical standpoint, you do want to have as relatively close as possible as far as speaker wire length so that all the signals get to the speakers at the same time and they are synchronized. But, if you are within a few feet, you will not even notice the difference as electrical signals travel extremely fast.
If I may give you one more suggestion, which I believe should be the most important, is to make sure you get a thicker high quality speaker wire. The thicker the wire, the less resistance there is for the signals to pass through the wire and the less information you will lose to your speakers. Speaker wire is sold in a unit called gauge or AWG. The lower this number, the thicker or larger diameter of the wire. I would suggest a 12AWG size wire to maximize the performance of your Aperion Audio speakers. You can get really cheap but high quality speaker wire and HT stuff in general at
www.monoprice.com
They seem to sell this stuff cheaper because no manufacturer slaps their logo (i.e. Monster) on the packaging.
I hope this helps and I hope you enjoy your speakers.