In short yes. If your company is able to reach users via offline channels (television, print, radio), those same users are likely to search for your website directly, and the SEO community knows with some certainty that large numbers of direct users who are satisfied with the site's offering, whom convert and then also return to the site, tends to result in high organic ranking positions. This has been the case since the Phantom quality updates in mid and late 2017.
For a little more information, read the section on 'User experience signals from Non Organic channels' from my last post.
The ideal way to ask for backlinks is to not, but if you must, the only time asking is acceptable is via legitimate guest blogging, whereby you provide a piece of content that you and the webmaster you have a relationship with believes will be found interesting by both his/her audience. This should never be for the exchange of money or goods.
If your content is uninteresting to everyone, it is undeserved of authority. By all means, offer your content for free to as many relevant websites as possible, but more often than not, if your content is offered in the right places to the correct audiences, you'll acquire backlinks naturally, in exactly the way Google advocates.
This is not an easy question to answer, since it will depend on the circumstances. Where possible, my advice would be to keep SEO managed in-house and to use an agency when you know exactly what you want to accomplish. The reason I say this is because most agencies will offer you a templated workflow that is scalable and cost effective for them, but which does not necessarily help you achieve your specific goals.
Hiring an experienced SEO to manage the SEO from within, who knows both how to achieve results, and how an SEO agency works is the best possible solution. In this way, you can define very specific goals from the first meeting with the agency and ensure these goals are met within a 6 month period. I say 6 months, because this is usually the minimum amount of time a competent search marketing professional requires before yielding positive results. This is even backed up by Google.
Ensure all costs are broken down, so you know exactly where each pound is spent, and review absolutely everything from a technical and linking perspective before it is implemented.