There is setting available in general setting where you can set who will have which GUI.
If theme integration is set Yes, it will load support plus in your theme. In case of design issues, please create ticket, our agents will try to give custom css to make it compatible properly. Otherwise, Non-Integrated GUI should work without any problem. You can still adjust colour combinations of the Non-Integrated version in Customize section of settings.
No, shortcode is not required. You can just select support page in Support Plus > General Settings.
You can only purchase available Bundle. Bundle prices are affordable as good as single individual add-on.
Below are few simple steps to upgrade add-ons for WP Support Plus 9.0.0