B&H is great! Fo lens cleaning (dry), I use the cloths they sell for cleaning my glasses. They work great. Aaron, you shouldn't need to wet clean your sensor unless you have been through a dust storm. A rocket blower will get rid of the dust on the sensor. If you need to do a wet clean, be very careful and read up on it before tackling the job. You don't want to mess up the camera when cleaning it. That's not to say you will, but just read up to know what to expect before going through with it.
I don't like the lens cap leashes because there are times I am moving my lens quickly across a pan shot, or in the open cockpit of an airplane. That thing gets swinging around, or blown by the wind, and it gets in the shot, or hits you in the face. I make a practice of removing the lens cap and putting it in my pocket. Haven't lost one yet.
When buying lens filters to help protect your lens, don't buy cheap ones! The reason is that they can soften your focus dramatically, or create additional glare. I bought a cheap filter with my 50-500 lens thinking it would be great. I almost returned the lens because the focus was really soft. Then I removed the filter and took some test shots. WOW, that was the problem, the filter, not the lens. For the record, I have never used filters since. It's one more reflective surface for light o bounce around in. I don't recommend it for most people, but it's a choice I make.