If there is at least 1 person at the resort who has converted and is currently in RCI points, it is a points resort. Also non RCI points resorts that have their own internal points system where the developer can choose to deposit in either points or weeks are considered RCI points resorts(Hilton, Wyndham, DVC, etc). There usually are still weeks owners at a points resort and their membership continues the same as it always had with trading power (tpu).
If you own an RCI points week then your trading power is the number of points you have. You want to make sure your points to MF ratio is good. You don't want anything above a penny a point and the closer you can get to half a penny per point the better.
You can book for less than 7 nights into points resort inventory. Again just because it is a points resort doesn't mean a particular week that is deposited is in points. It could be in either. In some ways the only way to tell if it is in points is if it lets you book more or less than 7 nights in a single transaction. If you are booking 7 nights you can tell it is points because the exchange fee is about $30 less.
If you want RCI points you need to look for someone who has already converted and is selling. Buying an unconverted week at a points resort will get you an unconverted week. There are a few resorts that do not transfer the points with resale. I don't have a list. I know the Soleil managed resorts fall into this category. You would need to make sure you don't buy one that doesn't transfer as points. You will just need to do the research when you come to one you like.