Each of your examples has a different answer.
In example (1) it would be grammatically incorrect to say he try to find. This is not the type of mistake native speakers ever make, so it can only be he tried to find.
In example (2) the two sentences you list are likely (but not certain) to be pronounced differently in American English. In the sentence
He went ashore
the t may be stopped in the throat, not a plosive t.
He went to shore
Here we have the throat-stopped t followed by a plosive t on the to.
Of course, exactly how people pronounce these things depends on the accent being used and how quickly and clearly they are speaking. It is conceivable that in a noisy environment, one might have a hard time distinguishing the two, but then, they mean the same thing anyway.
In example (3) the only way to know whether she'd means she would or she had is from the context, but these two are unlikely to be confused because they require very different contexts.
She had is used to describe something she did only once in the past and then we discuss something that happens after.
She'd already cut the loaves in five places when she realized she had forgotten to add salt.
She would refers to something she did over and over in the past
I used to order from her deli every day. She'd cut the loaves in five places, just like I like them.
