Can I open word and pdf files on and download files to iPhone?

I have been using Nokia phones and Symbian OS for a very long period and considering buying an iPhone for the first time.

I was wondering if:

1) it is possible to view & edit word (or even excel and powerpoint) files on iphone?

2) it is possible to view pdf files on iphone?

Please comment if I need to install an application for viewing these files. Recommendations of applications is greatly appreciated.

3) Assume that I sign on my email account and want to download the attachment file of an email to the internal memory of the iPhone. Is that possible? If so, does the iPhone let me where (specific folder for instance) to download the file? For instance Symbian OS pretty much works as Windows where there are already-established folders within the internal hard drive of the phone and I can create a folder if I want and name it how I like it. (I do not require the same from iPhone.

4) Is there a search function on iPhone? Is that really good? For instance on Symbian OS I can search a word/phrase and the results yielded are sorted according to the applications. For example, if that word is used under the phonebook, a couple of text messages and a word file within the internal drive of the phone, then 3 categories show up, and for example I click on "Messages" to see the text messages.

Yes, you Can open word and pdf files and download files to iPhone.iOS 4 received an upgrade allowing you to save PDFs to your phone using the iBooks app.iBooks is developed by Apple, available for free download from the iTunes Store and allows you to store and view PDF files and eBooks directly on your iPhone.