You create a new product, each product (or combined product "ie. Product+OB") has to have a distinct Product ID, in our app each product has two IDs, first for the product itself, and the second for the product when combined with an OB.
That's certainly a CF bug which I'm aware of, I personally usually refresh the page and it works fine.
In the SALES yes, in the STATS for some reason NO, Clickfunnels said they have a bug which prevents it from showing the STATS for non Stripe payments but since then it never been solved yet.
Yep, nothing except making sure that your Paypal account supports what you are trying to do, couple days ago, a member from New Zealand had an issue getting recurring payments to work, before we discover that recurring payments are not supported at all in NZ
Also you might want to configure your account only once to support auto-redirects in order for the OTO's redirection to work seamlessly.
Hope that helps, Sorry for delay,