I’ve written about a lot of this here: Adventures in Difficulty Bombing. An exercise in predicting the future… | by Thomas Jay Rush | Coinmonks | Medium. That link also has links to a bunch of other articles as well.
About the impact on gas price, I’m not sure. It has had, mistakenly I think, a serious effect (at least on the arguments surrounding) the block reward, but I don’t know about gas prices.