Is WP the ideal platform for my 'Multi-user' Blog?

Hi all,

Last week, someone referred me to this wonderful world called WordPress and I must say that I was really impressed with how powerful this magical platform is. Now, considering that I’m totally new to this huge world, I need some guidance from experienced WordPress users, on whether first of all, WP is the ideal platform to build my site with; and maybe give me some tips on how to develop the project I have in mind. Let me explain briefly what my project (which is a dream rather than a project) in a nutshell consists of.

(1) I want to build a voluntary community site, where anyone can self-register and subsequently can start submitting posts to the main page of my site. However I’d like that Registered Users can submit Posts only from the Front End of my WordPress site and thus, no access should be given to the Back end of my site.

In other words, what I’m after is like a blog but instead of having one person posting & feeding it; normally being the site creator/blogger him/herself, I want that any registered user of my site can submit posts to the site. Thus, having multi-users posting on the same blog in a chronological order!

(2) Then I must make sure that each post received in my blog, is not automatically published but will be received at the back end of my site for moderation and waits for approval of the Site Admin.

(3) I must also make sure that New registered users ensure that each post they submit, must contain the following:
(a) Content of the post (obviously);
(b) Title;
(c) Upload a relevant photo with each post which should be, upon uploading, automatically resized & watermarked;
(d) Post must be assigned by user to one of 5 pre-defined categories; previously created by site Admin

(4) Finally, I want that each submitted and approved post, will be automatically shown as a ‘teaser’ on the site; in the sense that only the first part of each post is displayed; with a link at the end of the post to access the whole story. Also its layout must be in a blog format and in a chronological order but must be specifically, in the following format:
a) Only the first 500 characters of the post will be displayed on the site’s main page; the rest can be accessed via a “Read More” link;
b) The image/picture/photo uploaded/submitted by the user with the post, will be shown on top of the ‘teaser’; that is on top of the first 500 characters; irrelevant in which part of the post, the user originally inserted the image. Thus image uploaded in the post by user is automatically extracted for ‘teaser’ purposes.

I appreciate if you can help me achieve my dream.

Thanks in advance,

Kevin