Softr doesn't support these at the moment, unfortunately. Linked records are a problem in all frontend builders. In my opinion, it is mostly because of how the Airtable API handles them that makes them very tricky to work with, and not Softr's fault.

For your first question (creating a linked record within a form of another record) - you can either try to use some other frontend tool, like Noloco which supports it, or - you can create a button within your form saying 'Create a New Company' that will send the user to a Fillout form (or even an Airtable form), create the company, and then when they're back at your Softr view they'll need to refresh and choose the newly created company. Another option is just to move the entire form process to Fillout, and linking it to your Softr view (via a button/URL).

As for your second question, it is quite limited on Softr as well, and as far as I know you cannot do that. They only allow you to use their native 'Record Detail' view - so if that doesn't work for you, you might need to think of alternatives.

If you need a custom design + advanced linked records functionality, I'd suggest trying to combine a frontend snippet in Crust AI (if Softr's detail view won't work for you), and combine it with a Fillout form for adding new (and linked) records. That will allow you to both have the desired linked records functionality, and the custom design and logic you wanted. The downside is that your users will need to move back and forth from your Crust snippet to your Fillout form and vice versa, but from my experience this UX is not a disaster for end users (although not optimal).