In this context, "if ever she" is really just the same as "if she ever":
If ever she stepped on her dog's tail, the dog would yelp loudly.
If she ever stepped on her dog's tail, the dog would yelp loudly.
Those two sentences mean the same thing, although the first has a more "poetic" or "literary" feel.
This is in contrast to the "if ever" in the expression if ever there was one, which is used to emphasize the truth about something:
If she ever stepped on her dog's tail, the dog would let out a loud yelp, if ever there was one.
In that sentence, "if ever there was one" underscores the loudness of the dog's yelp. That makes it sound like her neighbors could probably hear the dog howl, not just the people in the room.
The phrase in his own small way refers to those little things that people do that somehow make a big difference. It's often used to in situations where someone is doing something they would regard as something small – something they might describe as, "Oh, that's the least I could do" – but somehow their deeds contribute to a larger cause and have a big impact. So, suppose I worked with someone named Jane, and Jane was always cheerful and ever friendly. Perhaps we didn't really think much about it at the time, but now that Jane's been gone for a year after moving to her new job, people realize that the office just isn't quite as sunny without her cordial remarks. Someone might reminisce:
I miss how Jane used to light up the room in her own small way.
Jane, in her own small way, sure had a knack for keeping things cheerful around here.
The phrase is most often used in a positive context; for example, from a film review:
Though living on a small income, he has been magnanimous in his own small way to provide shelter to an orphan girl.
and from a news article about philanthropic work:
Paul Lazarus knew he wanted to do more – maybe even, in his own small way, help to change the world.
and from a blogger writing at Christmastime:
And, I always give a card to Jeff, the garbage man who so simplifies my life in his own small way.
However, it could be used in a negative context as well, as was done in this 1869 novel:
So he was vexed with her, and chafed in his own small way, and was jealous, as if her leaving him was a willful act of neglect, or indifference to his happiness.
In that example, his little irritations are having a big impact in his life, and making it impossible for him to enjoy his life.