1. On a 12 year old domain, what would be a safe amount of direct links to build to a site?
A: It really depends on what the current backlink profile looks like. I'd recommend getting Majestic SEO and doing some research on your current backlinks. Verify that there's been steady backlinks being created over the twelve years. It's a common misconception that having an old domain suddenly makes you not prone to penalties for backlinks. Just because a domain is twelve years old, does NOT mean it's okay to build a huge amount of backlinks in a short period of time, that would look unnatural to Google, and you'd likely be hit with a penalty.
If the domain has steady backlinks being built over the twelve years, you're probably safe to continue building more backlinks (while maintaining a verity of many different anchor texts, and page URLs.) However... If the domain does NOT have any backlinks built, or only has a few, I'd recommend starting off slowly with high value tier-1's (possibly hand built if you're willing to put in the time/effort.) Slowly increasing the amount of backlinks being created as pages with new content are created.
Remember to also look through any old backlinks to see if they're pointing to any pages that no longer exist. Find the URLs they're pointing to, and 301 redirect that page to your domain. This way, page rank still flows and you aren't missing out on any free links ;].
2. Why do seo companies always point to 500-1000 links per month, is this a perceived correct velocity?
A: There is no perceived correct velocity, as every website, and market is different. It's good to have a variety of backlinks built out to different pages of the website. This helps make your backlink profile look more natural to Google, and prevents raising any concern.
3. I've read guys on here doing blasts on here of 10,000 wiki links, could this penalise a site if rate is not maintained?
A: It could and most likely would cause a penalty if there hasn't been any backlink building over the brunt of the twelve years. 10,000 backlinks of any kind to a website that previously wasn't steadily creating them is going to look VERY unnatural.
4. For tier two and three, do you guys just plug in GSA and leave it run to infinity?
A: You could do that, sure. If they're not pointing directly at the money site, you're much less likely to get hit with a penalty. If anything, Google will just devalue those backlinks.
5. If you have batches of content, would you post it to site or use it for tier one? Or both?
A: Depends on the content, and whether or not it's worth even spending time on.
6. Spin (human readable 70 plus unique) or syndication?
A: I'm assuming you're planning on building this website out long-term, correct? If so, why waste a domain with spun content or blog syndication? Just spend the time, effort and money on creating/purchasing unique readable content. There are tons of websites where you can purchase uniquely written content from actual authors, not to mention the few very reputable service threads in the service forum here.
Good luck! Let us know how everything goes.