Not sure about order management, but you should check out seopanel.in - it's a free, open source SEO management dashboard that you can setup on your own hosting. It's not very user-friendly, need to get used to it but it does track everything nicely.

Depending on how you want to manage your orders, you can use something like WooCommerce that will be integrated into your WordPress-powered marketing site and allow you to do ecommerce functionality for simple ordering.

Feel free to request a call about either platform or both. Depending on your budget, I can recommend few other SEO platforms I've worked with that are premium but very good.

As far as I know http://raventools.com/ has a whitelabel option that covers all of your needs.

This is definitely a tricky question as many platforms and services for SEO reporting are out of date and not current with the newest search engine algorithm changes. As there could be 100 or more algorithm changes on Google alone, each month, you need a solid platform that is reliable and timely.

The two that I recommend you check out are Moz.com and Raven Tools. Moz is my preferred platform as the team is always on the cusp of breaking SEO news and changes.

If I can further help you, give me a call.