I think it's just her random, meaningless word for "Good morning".
I found an interview with the producer of Non Non Biyori.
What's the meaning of "Nyanpasu" from main character Renge Miyauchi?
The town of Asahigaoka is not explicitly based on any single real location. Of course, some location scouting in the countryside was performed for the sake of realism.1 Most anime these days engage in this activity (called "location hunting" / ロケハン) when appropriate - e.g. when they are set in modern Japan or something that looks like it.2
That said, the ...
I have looked this up before and found this:
But have you considered why “Nyanpasu” is a creative coinage of a new term in Japanese?
Japanese people and linguists may disagree on the exact etymology of the greeting “Osu!” This greeting is often used by people who are exerting themselves physically, such as karate students. (“Osu” is customarily used by men, ...
While there's no official statement from the author, it's possibly a combination of nonbiri (のんびり, carefree) and hiyori* (ひより, 日和, fine weather), which can be interpreted as "fine weather (or fine days) to be carefree."
This is strengthened by the fact that:
Outside of the manga/anime, there was also 「のんびりくえすと！」(Nonbiri Quest!) radio corner
This is the Monthly Comic Alive. It is a Japanese seinen manga magazine published by Media Factory.
Picture from comicvine
This episode here is the July 2013 issue or as a number 201309.
I am pretty sure the mange she is reading here is Omae o Otaku ni Shiteyaru kara, Ore o Riajuu ni Shitekure! (おまえをオタクにしてやるから、俺をリア充にしてくれ！)
Well, here's an album of all the cast credits from the first 9 episodes of Non Non Biyori: link. None of them list Suguru.
At minimum, then, we know that he hasn't had any lines so far. Maybe we'll have a big reveal in the final episode or something that Suguru actually does speak, but for the time being, I think it's safe to say that he doesn't have a ...
The manga on the cover is Seikoku no Dragonar. It has received an anime adaptation just last season (Spring 2014).
The manga that she is reading inside is Omae o Otaku ni Shiteyaru kara, Ore o Riajuu ni Shitekure! (lit. I will turn you into an Otaku, so please turn me into a Riajuu).
The pages are from the end of chapter 10. Below is the 2-page spread for ...
Ren-chan's "Frog's Song" is either a parody or otherwise an original song.
As nhahtdh commented, the song lyric couldn't be found outside of Non Non Biyori-related results, making it an original song. The song is also known to the fans as れんちょんのかえるのうた (Ren-chon no kaeru no uta, Ren-chon's "Frog's Song"). It can be listened on Nico Nico Douga, starting at 0:...