I converted my D300 to IR several years ago. Took some shots and then stopped. Decided to pick it up again. It was an old body that I wasn't using anymore, so don't regret the conversion. But a PITA to use.
Focus is a royal pain. Lifepixel will calibrate a certain lens, but different lenses will be off. Even the same lens if it is a zoom will be off at different focal lengths.
You pretty much have to shoot with either a calibrated prime or use Live View for focus.
White balance is pretty important, even if shooting RAW. Because it's IR, you are heavily reliant on the red channel and LR/photoshop don't let you adjust WB enough in post to compensate for the IR wavelengths. Shooting a custom WB with the camera aimed at a green scene helps with this.
Here is a shot from today that I liked the IR effect, but the focus is completely borked. May post more as I play with this more.
Image
Judging by your other photos, I think you can do better
I find it easier to focus with my 50mm prime, it requires only a small consistent correction that I just got used to doing right before I fully press the shutter. With a zoom, your saving grace might be to use a small aperture, as they are just completely a pain to correct. Most of my shots done with a zoom are not quite sharp, but passable, especially at web resolutions.
And something infrared from me, freshly dug out from the bottomless hole that is my library.

IR View from Rattlesnake Point by FriskyFreeze, on Flickr