'Sounds like Stefan & Johnus give you the goods. Getting to know a natural requires quite a bit of practice to get to know a rock. In that way, I think the naturals are over-rated - but that's another story.

On the rough spots - I'd ask Maxim about it, and what he recommends. That way, you're not introducing any actions (lapping, etc) that could make it difficult for him to provide good service - such as exchange or replacement. With that issue resolved, you need to be free to practice alot. IIRC, Holli4pirating once answered questions about learning to hone well: go do a couple hundred blades and most of these questions will go away.

Practice blades: good, sound steel, straight edge w/ no smile, at least 1/2 hollow, but preferably full or extra hollow. The reason for cheap is so you can make peace w/ the idea of practicing enough to wear it into the shape of a chopstick. If you're worried about blade wear, you're not free to experiment. This doesn't mean fleabay/antique store blades that need restorative grinding so you're ABLE to hone. A cheap blade - no beauty queen that has a sound bevel - meaning the wear surfaces of the spine and edge are already parallel and mostly straight - is a requirement for valid testing. If in doubt - send to a pro or experienced user and have them just set a good bevel for you. You'll learn much faster and thank yourself.

Others will have to advise on the use of naguras - I don't use them.

With no worries about blade wear, you can go have fun. If your 8k edges already give a nice shave - you're able to benefit from the use of higher grits - syth or natural. Go have a ball!