You need to fix IE8 to have it work properly with GMail, by turning off Compatibility View.
1. In IE9, press the Alt key to toggle the main menu bar on first.
2. Then in IE8 or IE9 click Tools and choose Compatibility View Settings
3. Remove google.com
from the big text box if it is there (in some versions it may not be.)
4. Uncheck the three checkboxes under the text box - this is very important, or Microsoft will just switch CV back on again next time you start IE.
5. Restart IE.
That should cure all your scrolling problems.
To deal with your sidebar you have three options:
1. Hover your mouse over the section you want to see to expand that part - i.e. mouse up to your labels to have them all drop down, or mouse down to the bottom to see your Chat contacts
2. Grab the bar which divides the two sections and drag it down till you can see all your labels
3. Collapse Chat till you need it by clicking the Chat bubble icon at the bottom of the side bar.