I'm not exactly sure what the first is called, but it's commonly used to link the current sentence to the previous one. Kind of like adding a relevant idea. A varied version of a semi-colon, you could say....with different criteria on the usage.
The second is called wakiten, and is used to emphasize words. In speech(quotes), the word highlighted in bouten is actually emphasized when the speaker says it. In writing(i.e. normal text), it often indicates a sort of irony. English writing often does this in the form of italics.
"If you actually tried, you would've finished it on time." as an english example. Of course, the choice in which words to emphasize often differs from english.