Listen to the router and you will be able to tell if it's going too fast or slow and look at how the wood is being cut, don't get to hung up on tying to get the correct speed. The router might tell you 10,000 RPM's but that's about as much use as your car telling you its going 3200 RPM's. It's all about the marketing it sounds good when your shopping for the router. For the boxes I would go with maple.Oak doesn't look that nice when stained. If your table doesn't have several size rings then you need to get or build a table that has them. Without being able to reduce the space around a smaller bit your are risking an accident, without being able to use a bit larger than the hole in the table you are limiting the router. It isn't normally necessary to measure the bit height just set it and see how it looks,. Depending on how high or low your bit is the profile will be different. Once you settle on what looks best keep a sample and mark on it what bit was used. As far as cutting small pieces on a miter saw, don't. If you absolutely need to then clamp them down using the fence and a block of wood.