Drupal 7.x

HI,

We've migrated our Drupal 7 site from one host to another ISP. Now the site has several issues and I am too much of a newbie to figure it out. I suspect a lot has to do with the rewrite rules and directory permissions, but don't know how to fix them. Here are the problems with which I would appreciate any help:

1. The CSS files and images are not loading. E.g. according to the source of my webpage it is calling many CSS files. Just to pick an example the first one is like this:
http://www.example.com/modules/system/system.base.css?lf77qa (I have my domain instead of the example.com part, of course.)
If I look at the directories via SSH/FTP I see that the system.base.css is in the folder where it should be (/public_html/modules/system/system.base.css ) So why isn't it loading ? (If I got to the URL http://www.example.com/modules/system/system.base.css I get a 404) And what does the "lf77qa" part do at the end of the URL?

The same applies to my images they are there in the directory structure where they should be but they are not loading; e.g. http://www.example.com/sites/default/themes/mythemes/acq_sky3/screenshot...

2. I get a lot of error messages like this on every page:

Hi all, we have a request for a simple report that will show # of log-ins by domain, # of log-ins by specific users within a domain (e.g. joe@xxx.com, sam@xxx.com), and content accessed by users within a domain.

The output would look something like:

Hello all,

Is there a way to have the option where all users can create containers and not just forums?

Hi all.

I'm just setting up my first Drupal 7 site (I have a few Drupal 6 sites under my belt). The new site is just a simple informational site with articles that will be added periodically over time. I'd like people to be able to subscribe to my new site's RSS feed if they want to keep up with new articles.

I get the following error after upgrading to drupal 7 every time I edit a post:

---
Notice: Undefined index: required in field_default_form() (line 76 of /modules/field/field.form.inc).
---

Can somebody help me to solve this problem? Thanks.