Hello,
1. Please add this code in Theme Options > Styling > Custom css:
.single-product .quantity.buttons_added input[type="number"] {
padding: 0 0.1em;
}
2. This line relates to your footer so please check Appearance > Widgets > Footer areas.
3. You may disable “Enable Sign In link” option in Theme Options > General > Header settings.
4. Please provide screenshot. You may use such screenshot maker as Lightshot.
5. Please describe the desired result in more details.
6-7. You may disable tabs on single product page in Theme Options > E-commerce > Single Product Page > Tabs type.
Regards