Hey, OP! Post your IGN so we can send you free stuff. I can't help you too much with interface issues because I don't use a common viewer, but I've given people the general walk around before.
There are some newbie regions: http://secondlife.com/destinations/howto/newbie
You might be able to find someone there to help you out, though it's best to just get inworld with someone more experienced and have them show you around.
Anyways, here's the answers to your questions.
Camming: Alt makes you zoom. Ctrl-Alt orbits your camera. Ctrl-Alt-Shift lets you pan. Zooming into your avatar a lot can activate first person (mouselook) view. Escape, or just moving around a bit, can reset your camera.
Try going to a store, and instead of walking around, stand in one place, and look around. When you get better, try doing hunts- they're events where shop owners leave out gifts with hints. The hunt items are often small, so you'll have to cam under chairs or behind panels to look for them.
Changing your avatar / wearing shit: Open up your inventory. To put items on, right click them > Add. Clicking "Wear" may knock off other items that occupy the same attachment point. The library works a bit funny so try experimenting with some freebies you find on the Marketplace.
Since you're new, you may be wearing a starter mesh avatar, which can be confusing. If your viewer has a worn tab, go to it, find the folder your outfit is in, right click it, and remove it. This should let you see what the real SL avatar looks like (significantly worse.) But its the one that responds to all the sliders.
To change shape and stuff, right click your avatar and click on Appearance. Shape sliders should be under there. On most viewers, I think that worn items should be there as well.
To edit items on your avatar, right click them and select edit. You should then be able to scale, rotate, or move the item (if it's mod.) If it's no mod, you can still move and rotate the object. If it's rigged mesh, you can't really change the position. The edit menu has a bunch of options for texture, properties, contents, etc. Go to the texture tab to change the tint on an item. If you want to select individual bits, click on Edit linked parts. To select the faces (areas of a single mesh/prim that can take different textures and thus can be tinted separate), there's an option for that as well.
Roleplay is a major activity on SL, for obvious reasons (character creation has few, if any limits, there's a chat system, and even a script system to roll dice/change the name you type with/etc.) Some communities are mostly into RP, and some like messing around. For example, your typical fantasy sim will be a bit serious and ask for logs and have a bunch of factions, but a furry ERP sim is more of an informal hangout place.