Note that personification is not really the attribution of human characteristics to abstract ideas; it is instead the construction of a fictional paradigm who represents or embodies abstract ideas, as in the blindfolded female figure that represents Justice, etc. This is a small but important distinction.
Personification may also refer to a person who embodies or epitomizes a certain quality, or concept, or even a thing, as in "Winston Churchill was the very personification of wartime leadership."
Modest and decent have overlapping semantic ranges. They can mean the same thing, but do not always. To further confuse things, they might get used in the same situation to highlight slightly different aspects of a thing.
Modest can mean behaving in a way that does not draw attention to oneself, of which clothed in such a way that it conforms with sexual norms is a specific case. It can also mean simple because simple things do not draw attention to themselves. From simple, the related meaning of not wealthy or not opulent emerges.
Decent can mean meeting expectations without having the connotation of exceeding them. It can also mean a morally good person, though not necessarily a heroic or saintly person.
Here we have the area where the two meanings overlap: they both imply good in a way that does not attract too much attention. But they are not always interchangeable.
So as to your sentences, I believe the average American reader would consider the sentences about the house to be more or less equivalent. The average American, though, would sense a slight difference in the sentences about the woman, because "decent" is a broader category than "modest". A woman might dress modestly, but lie, cheat, and gossip, none of her acquaintances would call her "decent".
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They're generally used synonymously these days, though there was originally a distinction in meaning. "Ill" generically referred to being unwell, whereas "sick" referred to vomiting — this still persists to some degree.
In modern times there has been (and still is to a degree) a distinction between upper-class and non-upper-class usage in British English. See the Wikipedia article for example. The upper-class usage, unsurprisingly, seems to preserve the more traditional meanings of the two words.
Finally, if you're curious you can take a look at the etymologies of sick and ill. The latter originally only meant "morally evil", curiously enough. This is going back to the high Middle Ages, however. Meanings have been are still in constant flux.