differences between Helios and Venus:
Venus is bigger because of the batteries, also weight is 160 grams more.
Helios has some improvements in the electronics, for example the vapor light can be active during the sessions, in Venus it is only available when boosting.
Helios runs with a 12V power supply, and Venus is designed for 6V because of the batteries. Availability of 12V Halogen bulbs is much better, so spare part can be more easily acquired locally.
Helios has 50W powered bulb and it is optimized for this. The fact that Venus runs with a 6V 50w bulb does not mean it is optimized for that. For example, the boosting power cannot be adjusted in Venus, and the full boost power at 50W can easily be too much, and this has been improved in Helios in the design and it even has the adjustable boost power from 20% to 120%.
Helios has more interesting visual effects in terms of "breathing LED" during warm up.
Helios has the HerbSense -technology which means that it conserves the taste of herb during relaxed sessions when the vape is sitting idle, by reducing the power in such situations.
3. Venus is not available at the moment. It will return later, now I expect it to be available in January.