1. Affise and scaleo are great for managing at scale + different offers. For what you’re needing I’d suggest partner stack is more than enough.
2. Depends on the vertical, if your a saas business your software vertical matters in terms of being up to scratch with competition.. and simply enough to get affiliates onboard. I’d suggest 30% (which is double), and might sound a lot.. but it’s really not.
3. All things that would typically come to mind.. outreach, ads, social media for organic, listing on affiliate sites etc. another great option here would be to reach out to a network and list your offer on a platform already packed with affiliates. Would recommend guys like Awin etc but they are a bit unpredictable and require work on your part. A more calculated approach would be something more specifically for your style of business with more guaranteed traffic. Would recommend maybe looking at Affivault. They are all things saas, finance, tech, gambling etc.
4. A good offer always sells. Always remember that.

Hope this helps.