The text atm is choppy, and ive seen some forums with clean cut arial style font all over using IPS 4.0 . Is there a setting or mod for this?

You would have to make a change to you custom.css file. You would do that in the ACP by visiting Customization > Themes, and clicking on the </> icon for the relevant theme.

 

This will bring you to a screen like the following:

Click on 1, navigate to 2, and then enter something like 3. In your case, change where I have 'DejaVuSans' to 'Arial', so yours will look like

body {
    font-family: 'Arial';
}

If you're happy with how it displays, you can leave it like that. If you need to change the font size to make it look better to you, then you'll need to add an alternative font-size like I did in mine.

Can I write all the fonts I want in there? Im interested in a couple of the google fonts. 
How do I decide what text should be the one or another font, and if its supposed to be bold or regular?

STig