Mochi is a very common sweet, a glutinous little dumpling made of pounded sweet rice, often with sweet bean paste in the centre. The most widely-sold commercial brand, which you see in Japanese and Chinese stores in North America, is called Daifuku. They are delicious:
(click to enlarge)
I am eager to see any show from KyoAni, but I have to say that
K-On was one that I abandoned after a few episodes. Much as I enjoy moe, there just wasn't much
there there, for me. And this show is another original from the director and writer that made
K-On.
Hyouka and
Chuunibyou are the KyoAni shows I have liked best since
Haruhi I.