Like another poster said, you are just completely running on your 'intuition', thinking he will do the things that you are kindof drawn to, while thinking he will not do the things you find unappealing. If he is not sincere on some things, how do you know he is on others?
On 'many' Mexican immigrants being those things trump says - do you have any actual numbers? data? statistics? or again are you running on your 'intuition' that 'many' are 'probably' bad or getting into bad things because they are presumably poor and uneducated?
How would you propose rounding up 11 million illegal immigrants? How many resources do you dedicate towards this goal? How much time? You know the government already investigates and takes action on cases, right? What would be changed? Would it become a witch hunt? "Call 999-9999 to report someone you think is an illegal"?
On your belief that he will not try to claw back on things like marriage equality, etc. Remember that even if you presume trump will be nonchalant, not care either way and so not actually take action, he will not be the only person in government that can push for it. If trump wins, there will be a whole lot of Republicans (Tea Party or otherwise) in government who have and do push for things that you think trump won't bother with. The Supreme Court nominees put into place alone would fully still be able to reconsider these things without the personal involvement of trump. The President is not the instigator of everything they or the rest of government look at. Trump's nonchalant attitude would then be something that could allow a flood of terrible ideas, motions, laws, etc. to be put forth and passed by other people, even if he takes no active part. You can see a scenario like that already in the reporting that trump plans to leave everything to Pence, who is anti-LGBTQ.
Trump proposes vague goals and objectives left and right, changing them as he feels in the moment, like you have noticed. That is what you feel good voting for?