Learning Spells, Scrolls, and Memorization

Playing an Arcanist, if my character finds a scroll of a spell he does not know, RAW say you can learn a spell from a scroll. The scroll then disappears, consumed by the aetherial flames. Can I then scribe this spell at a later time into my library or traveling spellbook? If I know a spell, do I always maintain knowledge of it and my ability to scribe it regardless of what resources my character has with him or her? If stark naked and without a traveling spellbook, library, or set of scrolls, do I still have my knowledge of spells and could scribe scrolls if given parchment and quill with ink?

Provided you have space in your travelling spell books and make the learn spell test.

As far as I know yes, when you are at your library of spells then you can transfer any new spells to your permanent spell books.

Providing you have the Scholar skill AND know the spell then you can attempt to make a scroll for that spell.

As always these are my answers, I may be wrong.