Alright here's my crack at your questions...
1- RE: brushes: When you install a new version of PSE, all the "standard" brushes, textures, filters, bells and whistles are there.
If you haven't been out collecting and using brushes etc created by other people you do NOT need to worry about loading more brushes into your new version of PSE.
2- Textures and filters: Textures and filters can be applied to any layer in your document. You might do use a filter on a picture to make it look like it was created with colored pencils. Filters can be overwhelming at first. There are a lot of choices there. Denis Gremain of eScrappers has a great
filter guide that helps explain what each filter does. I still use a lot of trail and error on picking filters when I'm trying to achieve a certain look.
3: Masks - Masks are basically a way to affect how much of your picture is shown WITHOUT directly editing the picture. So at a later date you can reopen your PSD file and edit the mask and change what part of your picture is shown. For more information check out this
tutorial on masks in PSE.
HTH! if I misunderstood any of your questions or you need more help, please post!