Recently a friend of mine gave me his bonsai to take care of as he's pretty feckless about them and was concerned he was killing it. I don't know quite why he gave it to me, I'm equally clueless (the only other bonsai I had was years ago and it died a swift death) but I like trees, so maybe that makes me more qualified somehow.

About the tree: he bought it from a one-time-only house plant sale at a student Union for about ...£20. So already highly dodgy! According to the vendor the tree is ten years old, and has been grown in Holland and imported over to the UK (so it's probably a mass-produced tree). I don't really know much about bonsai but I thought ...£20 sounded pretty cheap for a ten-year tree. Despite the dubious-sounding details, the tree seems to be in quite good condition considering it's mass produced. My friend had the tree for about a month before he gave it to me, and I've had it for roughly a week.
The first problem is, I'm not really sure what type of tree it is. The label that came with the tree has no information about it, only the bonsai 'brand', which is Herbae Optimae Formae. Judging from the other pictures in the Gallery I've seen, I think it could be a Chinese Elm. Can anyone confirm this?
Also, I'm not too sure about the conditions it's been kept in, but it seems to be shedding leaves pretty rapidly. I don't know if this is part of the tree's natural cycle given the time of year or if it's due to bad watering/keeping. At first my friend watered it by submerging it for about thirty minutes every other day - from the so-called expert vendor's 'advice' - but shortly after that it started shedding leaves pretty drastically. I've read that it's a very bad way to water, so since he gave it to me I've let it dry out a bit and watered it once from the top-down with some feed.
I've also noticed that a lot of the leaves tend to go yellowish, particularly around the veins, before they fall off. I've been told this could be either down to temperature or watering? I live in a third-floor attic room with a skylight, and it's pretty cool and light most of the time. Are these ok conditions? Also, what about pruning? I think it's in need of it, but I'm reluctant to try it for fear of cutting off new leaves.
I've attached some pictures. Sorry the quality isn't great.
Main tree after I watered it
[img]https://i222.photobucket.com/albums/dd225/Papasma/DSC01681.jpg[/img]
Another one
[img]https://i222.photobucket.com/albums/dd225/Papasma/DSC01683.jpg[/img]
Close up of the leaves
[img]https://i222.photobucket.com/albums/dd225/Papasma/DSC01687.jpg[/img]
Cheers and apologies for the newbie questions.