It's okay. Just a random filler. and much fanservice (such as the return of baby!Gokudera and the hot spring water battle... with future Varia and Vongola, except Tsuna's future self which sucks). But it's enjoyable and lighthearted. A great way to break away from the serious tone.
Yup! I've seen it before and even bought the DVD~ :)Why the question? I thought all khr fans knew there was an OVA.... I think it came out in 2008 or 2009.