Neck fit looks similar to mine and several others being built. I used natural timber mate to fill the gaps where neck joined the body and it took the dark red stain quite well. If going natural you may need to find a better coloured filler to match the timber.
As for the dent, some folk have success using a damp rag placed over the dent and then applying heat via soldering iron held to the damp rag.

Sent from my SM-A520F using Tapatalk