I believe so. The Presidency is the brass ring, and competition for it heats up (as we've seen) much earlier. Also, the money generally isn't there for hyper-extended Congressional campaigns.
As to your other points: true, Trump is no pure conservative, like Cruz appears to be. There will doubtless be things that he does, and people that he appoints, with whom actually conservatives disagree.
But this election is different, and not just because of the odd-ball characters involved on both sides. In fact, the odd-ball characters are a symptom of how different this election is. This will be a watershed election, and will likely be compared to 1932 and 1980. People clearly sense that we are very close to going off the rails - not the least reason for which is that we have a President, most of his administration, a lot of people in Congress and most of the media who either don't know it because they are simply too stupid, or don't care (and I'm REALLY giving them the benefit of the doubt in both cases), or they're doing it by design (and, in Obama's case, that is my position - NO ONE is that stupid or uncaring, NO ONE).
Sooooo, enter the common man: that's most of us, the people that get up in the morning and go to work, the folks whose parents and grandparents largely saved this country in WW2 and the Cold War, and who absolutely DO NOT WANT THIS NATION TO GO TITS UP. We all KNOW that insanity is defined as doing the same thing over and over, and expecting a different result. So, this time, we're not doing the same thing. This time we DON'T want a career pol, because those guys, either through design, corruption or sheer stupidity, put us in this mess in the first place. Off the lifeboats for you! Who's left with a chance in the Republican primaries? Fresh faces, some pols (like Cruz and Rubio) and some not (Trump & Carson). The rest are somewhat entertaining flotsam that will soon be jettisoned. Rubio won't make it - because of the immigration issue and because (as Cruz will point out in ads) he's done little else of note. Carson, while a nice guy and a smart one, is not Presidential timber. He has NO foreign policy experience, no managerial experience and no negotiating experience. He's the Chauncey Gardener of this campaign (from the film "Being There" with Peter Sellers). Hillary will destroy him if he's the nominee, and I think that most people understand that.
So, we're basically left with Trump and Cruz. The question then becomes: "Which one has the better chance of being elected?" I believe that the answer is Trump. The conservative in me recoils at a NYC resident who cavorted with and donated to a bunch of the worst Dims in the country being President, but NYC was where he was and he had to deal with it - as a businessman, not a pol. An advantage of that is that he knows who these people are, from an outside perspective, and I firmly believe that he despises them. Additionally, while Trump is hard to label from a conventional American political POV, I would say that he's best labelled as a "Nationalist." That will be a hugely (or should I say, "YUGELY") refreshing change from the America-hating, world-government loving, Moslem-enabling jackass now occupying the WH, and it is why I believe that he will win.
The Dims won't, of course, go without a fight, and the nastiest one possible, but they will be shown the door and told not to let it hit them in the ass. Ironically, IMHO, the Dims have become the status quo party, the one that doesn't want things to change AT ALL, because they've mastered DC (at least vs. the incompetent boobs with an "R" after their names). As such, they have a choice between a washed-up old hag with substantial legal difficulties who is the very definition of a "lying sack of $hit," and a washed up, grumpy old Socialist from Vermont who still has his very annoying and thick Brooklyn accent despite not having lived there in 47 years. Wow, what a great choice! Trump will beat either of them, or even a "drafted" Biden/Warren team if Shrillary implodes or has a stroke.
So, IMHO, Trump is our next President. Also IMHO, the best move that he can make is to take Cruz as his Veep, because that'll give the ticket a little DC gravitas, plus a man who is basically married to the Constitution and who is possibly the only person in the field smarter than Trump. Cruz will keep Trump on the straight and narrow Constitutionally (VERY important after Obama), will guide him on Federal judicial nominees, will act as liason/whip with Congress, and he will also help Trump clean house in the bureaucracy. Another clear advantage to that from the POV of conservatives is that Cruz will be the clear favorite in 2024 (or even 2020 if Trump decides that he's had enough of the corrupt idiots in DC by then).
Just my $0.02.
"The Dims won't, of course, go without a fight, and the nastiest one possible,..."
It will be spectacular because they know there's a good chunk of their troops that will vote Trump.