1. Is it difficult to install a dome lifter on an existing Yurt?
Probably not difficult if you can get one made for your yurt
2. For the bathroom & kitchen I was going to install venting fans. will that be enough for their intended uses?
I think so.
3. We were also going to install a ceiling fan under the domes for air circulation (reversible for circulating hot or cold air)
Will help with
but probably not help much with condensation.
5. Are there other ventilation options I should consider that have been highly successful?
A through the wall vent kit would probably do what you need. I assume you are doing something similar in the bathroom.
6. Would installing an interior vapor barrier over the insulation help or just trap moisture?
Yeah, would likely just trap moisture.
7. Any other recommendations for air exchange systems that would be low to no energy intensive?
A dehumidifier might do the trick too.