What are the best tools to find the right keywords for my custom intent campaign?

Campaign is not delivering because the display list is too short... Youtube Feed reach would be 200.000, because of the video viewers. Why is that 0 at the display list?

I run a search ad for the most relevant keywords for my offer. The ads were super profitable and spent was a couple hundred $ a day. But since a few days it stopped spending. It only spends like a 100$ a day. Whats causing this and how can I fix this? Thanks in advance for your help!

Google and Brian recommends using 10x of your expected CPA as the campaign budget. If my expected CPA is 50$ than I need 500$ daily budget for the campaign. But what if I can't spend 500$ daily on just one campaign as I have other campaigns running. Should I use a lower conversion event to optimize for e.g. vsl optin instead of booked call? And go with 250$ daily? Or whats the best advice for this situation?

Whats the best bidding strategy if I want to drive traffic to a homepage funnel. (no traditional vsl optin funnel) ? Should I still use TCPA? I use TCPA in my current campaigns running. Google says that the campaign is limited because of the TCPA. Daily Budget per Campaign is 150€. TCPA is set to 100€. Conversion goals are visit second step in funnel (formular) and booked calls. Thanks for your help in advance!