The analyses of a text #1

The protagonist, Philip, who was born with a club foot, moved in with his uncle Mr. Carey, the Vicar of Blackstable after his mother's death.
The Caresy's friend Miss Wilkinson visited them to stay at Mr. Carey's for a couple of weeks and she came to fall for Philip.

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There was a tennis-party at the vicarage, and two girls came, daughters of a retired major in an Indian regiment who had lately settled in Blackstable.
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It happened that they played tennis quite well and Philip was tired of pat-ball with Miss Wilkinson (she had only begun to play when she came to Blackstable), so when he arranged the sets after tea he suggested that Miss Wilkinson should play against the curate's wife, with the curate as her partner; and he would play later with the new-comers. He sat down by the elder Miss O'Connor and said to her in an undertone:
"We'll get the duffers out of the way first, and then we'll have a jolly set afterwards."
Apparently Miss Wilkinson overheard him, for she threw down her racket, and, saying she had a headache, went away. It was plain to everyone that she was offended. Philip was annoyed that she should make the fact public. The set was arranged without her, but presently Mrs. Carey called him.
"Philip, you've hurt Emily's feelings. She's gone to her room and she's crying."
"What about?"
"Oh, something about a duffer's set. Do go to her, and say you didn't mean to be unkind, there's a good boy."
[Of Human Bondage by Somerset Maugham]
1. I'd like to know if "what about?" means "what it was about?".
2. I'd like to know if "do" is used to stress "go."
3. And I'd like to know what "there's a good boy" means.
Thank you in advance for your help.