I'm not so certain about the nomination. Cruz has been outmaneuvering him on the delegate side thus far. If Trump falls short of clinching it outright, its entirely possible that Kasich and Rubio delegates could go to Cruz. If neither Cruz or Trump can clinch a second ballot, it could get interesting real quick.
Having followed GOP convention antics very closely the last two cycles, I can say with some authority that shenannigans are the norm not the exception, and anything can happen. Much will depend on Paul Ryan, who as far as I am aware will still be chairing the convention. Whether he decides to play a passive role and let Trump steamroll the event, or decides to play kingmaker.
If the GOP was smart (theyre not), they would be crunching data to factor in who might stay home on election day relative to each candidate. Their objective should be to keep control of congress. Conventional wisdom says that will be difficult with Trump heading the ticket. But it would also be difficult with Cruz. GOP is just fucked, and they did it to themselves.
After thinking on it a while, I have decided that Trump is actually less scary than Hillary though. Hillary is Saruman, where Trump is just Dr Evil.