Yes, Pro-Line recommends that all tires with closed cell and regular foam inserts (including Pre-Mounts) have 2 holes in the tread to prevent air from being trapped in the tire.
The color dot is something that Pro-Line has added to the sidewall of all our tires. This identifies the compound of the tire.
Watch how to Fix your Premounted Tire Wobble
Typically the more firm the material the longer the tires will last. Also, the more aggressive the tire tread design the longer the tire will last because there is more material.