I need help with 2 fields on my form

1. I would like the "Shipping Address" field to be hidden unless certain options are chosen

2. I would like the "Donation Amount [via PayPal]" field to be populated by a sum automatically, according to the option chosen, the same way that "Donation Amount" is done.

1. I would like the "Shipping Address" field to be hidden unless certain options are chosen

You can create a condition to show it depending on the other fields' value. Please see this guide on How-to-Show-or-Hide-Fields-Base-on-User-s-Answer. You can make the "I would like to donate:" field as the trigger.

Here's what the condition should look like:

2. I would like the "Donation Amount [via PayPal]" field to be populated by a sum automatically, according to the option chosen, the same way that "Donation Amount" is done.

You can add a Form Calculation widget to the form and make the calculation of the sum there. Or convert the Donation amount field into one instead. Then pass the calculated value to the PayPal field. Please see this guide on How-to-Pass-a-Calculation-to-a-Payment-Field. 

Thank you for the help with the first
I still don't see how a Paypal payment field can also be made into a
calculation widget
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I'm sorry for the confusion. Please add a Form Calculation widget and set it to hidden. Add the "I would like:" field in its formula:

Please keep the PayPal payment field as-is. Just set its payment type to "USER-DEFINED AMOUNT" then get the price from the Form Calculation widget as shown below:

Yes of course - I agree
but for some reason, my Paypal field properties don't seem to provide me
with choices but look like this:
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Please try disabling the option 'Suggest an amount' from the payment field so that the calculated field can be passed to the payment field.

Thanks!

I did try that also and it didn't help
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This is due to the Donation Amount field is not a calculation widget. Please note that the Payment wizard can only read the values from the calculation widget. I have now added a new Form calculation widget to pass the value from Donation amount and changed the setting in the payment wizard to read the Form calculation widget value on your form.

Please check again and let us know if you need any further help. We will be happy to help. 

Thanks so much!
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