The analyses of a text #1

Now the protagonist Philip is an obstetric clerk
He came to a mother's to give a treatment to the mother and her child on a Sunday.

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"I was just going to dish up this minute," said the woman.
"Fire away," said Philip. "I'll just have a look at the son and heir and then I'll take myself off."
Husband and wife laughed at Philip's expression, and 'Erb getting up went over with Philip to the cradle. He looked at his baby proudly.
"There doesn't seem much wrong with him, does there?" said Philip.
He took up his hat, and by this time 'Erb's wife had dished up the beefsteak and put on the table a plate of green peas.
"You're going to have a nice dinner," smiled Philip.
"He's only in of a Sunday and I like to 'ave something special for him, so as he shall miss his 'ome when he's out at work."
"I suppose you'd be above sittin' down and 'avin' a bit of dinner with us?" said 'Erb.
"Oh, 'Erb," said his wife, in a shocked tone.
"Not if you ask me," answered Philip, with his attractive smile.
"Well, that's what I call friendly, I knew 'e wouldn't take offence, Polly. Just get another plate, my girl."
[Of Human Bondage by Somerset Maugham]
1. I think "so as" means "so because."
if so, I'd like to know if "so as" in this case is idiomatic.
2. I'd like to know what "I knew 'e wouldn't take offence" means.
Thank you in advance for your help.