Good questions, and something I am aware to yet explain on the site. I haven't yet, for the two questions you just raised, being I'm still thinking about the exact wording, as it was the first thing to come to me also.
First off; Is that accurate?
Pretty much, with caveats.
I must be sure you either have PTSD or aspects of symptoms are being discussed in your blog otherwise. If I know you have PTSD, i.e. member here and you discuss it here, then your blog can be whatever the hell you want.
Yes, the connection is that you have PTSD or support it, but your blog can discuss everything and anything. Life... really, is what a blog is about.
My blog on the site contains everything... symptoms, life, relationships, health, you name it, if it happens in my life, I will likely blog it, regardless its connection to PTSD.
Put it this way. If you're a member here and want to create a site to market your artwork, which you do as a therapy to help you maintain your PTSD, then that is your site. Your blog would be an ongoing posting about your creativity, thoughts, artistry, and contain a shop to sell your artwork.
This is why I need to really impress in the opening pages, to contact us and have a conversation with me, as each accepted blogger will be case by case, individual needs and wants.
I would rather have 50 passionate, near daily bloggers, who have their site and maintain it ongoing, than have 10000 sites, most of which are spam, ignored after their first post or few. 50 passionate, committed, daily bloggers, will drive the marketing for all other 49 bloggers. 50 passionate, committed bloggers will achieve more for themselves and the other bloggers, than 10000 would, most of which are nonsense / abandoned.
If we have an Etsy account (or similar)... Is that something we could link, or sell directly through the blog's store?
A more complicated question. If you want to have your own shopping cart, then that is not merely linking to a third party. That is literally entering your item into your very own store, users viewing it, and if wanting it, they buy it directly through your site and checkout via Paypal or such. That is between you and them, basically.
I don't know anything about Etsy, though looked around and see they have an affiliate program. This means they allow people to paste code snippets into their site and create affiliate stores and such. Now... when such things are allowed, you can use their HTML or create your own links. Your blog will allow the basic HTML types allowed in a post, but cannot post them across your blog sitewide or such, as that requires my access to do, i.e. ad code insertion is usually a one time thing, thus I will post ad code into bloggers sites for them if they want it.
It's like Amazon, you can grab their images and host them yourself, which is typically faster, then link with affiliate code to their site, thus you get the affiliate commission. You can link to anything you want from your site, its your site. But a store is not PTSD Blog's store, but your own store, just like going to a site, shopping on it, checking out, that is what you can for yourself if you want.