Hi Dylan.
Love the question and unfortunately, my answer might be a bit premature since we haven't hired out the link building.
Having said that, we're in a similar position and we have accepted the fact that in order to turn the next "corner" in our evolution we must increase our domain authority and to do that are leaning strongly to hiring someone for our link building efforts. So you might find some of our story reinforces your own plans or perhaps gives you some things to consider moving forward.
The Backstory:
1. We have grown to the point that we need to revamp our site structure. I can hardly find my way around our site and I built the thing! So, I've made the decision to move to a new platform, implement a robust keyword suggest feature along with left navigation filtering. We'll also build out a top navigation with a hover flyout display for categories, subcategories and products.
2. Conversion optimization before link building? Yes. Ideally, all of this is happening concurrently but depending on staffing levels, staff capabilities, finances, etc. this may not be feasible. Before we invest in link building efforts we want to make sure we are converting more people with what we've got. I feel there is quite a bit we can do as shown in item one that will improve our conversion rate prior to investing in link building.
3. Anything to reduce reliance on Adwords is a good thing in my book. We've done PPC in house and hired it out with two different outfits. Right now, its just not a viable option for us and don't know if it ever will be.
4. Social. We don't engage it. There are various reasons for this and most if not all of them are out of my control. We're not dying on the vine because of it. There are a lot of things outside of social we are doing and will be doing to continue our growth.
5. In short - our link profile sucks. So hiring a company to help in that regard and should prove to be a good move for us in terms of building our domain authority. Once we get our conversion rate optimization under control, I'm looking forward to hearing what strategies different SEO's have in mind for us.
I hope there are some helpful/thoughtful nuggets in there that are worthwhile for you.
Good luck!