He only resigned as leader of his party, he remains as PM for now. There's a movement among the Conservative party - who are he only ones who can vote for a new leader - to cancel his resignation so he would stay on as PM.. The two candidates for leader are about as unimpressive as you could get. Suppose there was an inconclusive vote which Johnson declared invalid? And demanded a re-vote which included an option for him to stay on as leader?
I doubt Johnston has the authority to simply declare the leadership election invalid, that is likely to be down to the party executive or the 1922 Committee. Also, while it is a long established convention that the leader of the party with the most MPs is appointment PM, the Queen is technically free to appoint (and sack) anyone she wants as her Prime Minister, which acts as the ultimate check against any leader who really goes off the deep end.
The Queen won't intervene; never has. Johnson doesn't have to resign as PM, it's up the Tory part membership who they want.
He would be voted out on September 5th either way. The pro-Boris people will line up behind Truss for the most part
They don't play politics that way. Boris was responsible for ousting David Cameron. Boris was responsible for ousting Theresa May. Finally, Boris was responsible for ousting Boris Johnson.
I often get the feeling that the "conservative" party in the U.K. is little different from the more moderate arm of the Democrat party in the U.S., with maybe a few moderate conservatives thrown in. It's not really too much of a surprise they are a bit "lackluster". A conservative having any hard firm beliefs makes them practically unelectable in the U.K. these days. The U.K. voters only sided with the Conservative party because Labour went off the deep end.
No, they're actually conservative, while what passes for conservative in this country is radical, extreme, authoritarian, and even theocratic in nature.