Mountaineering for wimps

Hi everyone, this is my first foray into this branch, so please be gentle with me! ;)

3 friends and I have rented a cottage in inland Catalunya for a long weekend in about 10 days (from 11th till 15th June). We're planning on spending most of it in the pool or on the terrace, barbequing and drinking but we also fancy doing something a bit active.

Scandalously, I've never been to the Aigüestorts national park (near Sort in Lleida) so, even though we're staying a good couple of hours drive away, we're going to check it out but of course I have a few questions, so if any of you active, adventurous people have been, or know anyone who has I'd be really greatful for your input:

- Is it as gentle as it looks? A couple of my friends are really fit and could definitely deal with any sort of mountaineering, but my other friend and I are pretty wimpy. We don't mind doing a bit of scrabbling about on hands and knees, and we certainly don't mind doing alot of walking, but we don't really want to be doing anything that requires serious mountaineering equipment and we don't want to find ourselves half way through the trek with no energy and no easy way back.
- Is it doable for a day trip, given that we'll be spending 4 to 6 hours travelling (we don't mind leaving pretty early or getting back super late but still)? Or would it really be better to check out the refuges and try to stay a night?
- How cold is it likely to get? I know the sun will be beating down during the day but will it be much cooler than the coast? And will the temperature drop considerably at night? I can't imagine it ever getting cold in Catalunya in June, but I'm quite ignorant about that sort of thing.
- Are there any common pitfalls we should be aware of? Or just advise in general?

I hope those questions aren't too stupid, I'm really new to this and my friends are flying over from the UK for this, so I want it to be great!

Thanks so much!

(Cross posted on Western Europe)