Regarding the "dot 90," this refers to the dot above the 90 on the bezel of the watch, which is present on the original Speedmaster models from the 1960s. The dot is significant because it indicates the transition point from the black to the orange section of the bezel, which was used for timing purposes. However, not all Speedmaster models have this dot, and it's not essential for the watch's function.
As for the acrylic crystal, this is actually a characteristic of the original Speedmaster models from the 1960s, including the models that were used by NASA for space missions. The acrylic crystal was used because it is lightweight, durable, and shatter-resistant, making it ideal for use in space where the watch needed to withstand harsh conditions.
While some modern Speedmaster models come with sapphire crystals, the acrylic crystal is a hallmark of the original Speedmaster design and is highly sought after by collectors. So don't worry about the crystal, it's a key feature of the watch's heritage and adds to its overall charm.
It's great that your Speedmaster comes with NASA provenance, as this adds to the watch's collectibility and history. Enjoy your new watch, and wear it in good health!