If you want a step-by-step guide on how to use REW with Roon, then try this thread in the forum:
I was also an iTunes user for over 10 years and I too miss the vertical scrolling, the Roon team have said that this feature is on the road map, I know that doesnāt help you now but if you are willing to spend the time with Roon it will get easier, please donāt give up.
In the words of the great master Yoda, āYou must unlearn what you have learnedā
This is a downloadable PDF which I believe was maintained by a Roon user, I donāt know how up to date it is: https://1crm.com/docs/Roon_User_Guide.pdf
This video is also very helpful: Can we have a Manual please? [User Guide Is Live!]?
I never thought about using the keyboard to type in a name directly and I have had Roon for 18 months. Just taught me a new trick to jump to things quicker.