How to bond, gain trust & understanding? Very, very basically...
Start with being a Good Thing in his life. Horses learn by association, so make sure you're linked with the niceties. I don't think there is anything at all wrong with *appropriate & well timed* food treats as rewards either. Whether for training, strengthening/changing associations or 'just because', positive reinforcement is a powerful 'tool'. *Just be careful not to reinforce the Wrong things!
Set boundaries(or 'manners') & be consistent about them, but don't lose your temper or cause him to fear you when it comes to 'correcting' his 'mistakes'.
Bother to learn to understand him, his bodylanguage & natural behaviour & psychology the best you can, which will in turn help you communicate your ideas to him in a way he can understand.
Be considerate & fair about his natural behaviours & attitudes & work towards getting desirable and eliminating undesirable behaviour in a non-confrontational way.
Create a horse that is respectful to your boundaries, and you will have a horse that trusts you.
You can give him as many apples, carrots, pats and brushes as you like, but unless you give the horse a leader, he won't trust you.
Agree thoroughly with the second part, but not the first. I don't think consistently teaching horses boundaries makes them respect you(I don't think true respect can be forced anyway) or trust you unconditionally. But I do think it is a necessary step along the way.