#3. FB pixel attribution.
-Does the attribution only works for payment done through Paypal OR is it funnel-wide and it’ll work also with Stripe?
-I have read that I have to remove all the FB pixel from the funnel. Is that correct?
-What about the custom conversion. Can I leave them as is, so that they will fire normally? Also, should I leave the conversion value with the upsell price or change to $0? Because supposedly you’ll send the entire purchase value correct?
It works for all Payments, done through PayPal or Stripe or Cash on delivery (or other gateways), and yes it works funnel-wide as long as your funnel step has been added to your Funnelish funnel.
Yes! otherwise, you might get some inconsistencies… there is absolutely no need to have a single line of Facebook Pixel on your funnel to make it work, it works automatically (just like magic 
).
That really depends, on what events are you firing and how? and for what reason? Funnelish will automatically fire Purchase events for you with the correct purchase values no matter what your customers have bought whether it’s an upsell, downsell or order bump…
I also recommend checking this tutorial on firing custom events with the facebook pixel app