1) D&D has a tradition that if you want interesting robust mechanics, it must be magic. So classes have gotten more magic.
2) Give people the option of having magic in a magical fantasy game, they'll be inclined to take it. In real life you can be a good fighter, or a good thief. You can't be a...
Yeah, don't make it complicated or realistic.
Give Disadvantage vs ungrounded enemies or skill checks situations.
Have her be able to "see" in any lighting conditions.
Roleplay the rest.
Yeah definitely let the player know its a playtest and will be tinkered with.
I'd say take tree stride, change tree to bear in the text, and drop it down to level 3.
Also, bear stride is a great name.
One suggestion.
Just because something is a flying fortress/castle doesn't mean it has to look like an earth bound fortress or castle.
One castle could be carved to look like a giant statue of one of the lords himself or herself.
One a huge dragon standing on its hind legs.
An enormous jade...
The magical pseudo technology, the political intrigue left over from the Last War, the dragon marked houses and other unique organizations, the original races/different takes on standard races (who doesn't love dinosaur riding halflings, the high adventure aspect (which 4e embraced anyway.)
If...
Yeah I'd run Guardmore Abbey for sure.
Thunderspire is doable.
Definitely not Keep on Shadowfell or Pyramid of Shadows unless you want to do the work to make them better.
Reavers of Harkenwold is a high quality adventure.
I'd set it in Falkcrest (in the back of the DMG), do some small...