Two questions about our recent games :
1. when the final combat begins, do the following remain ?
a - lingering effects
I assume you mean "when the Avatar appears" some time on the fifth level of his keep.
Yes. Nothing says remove them.
b - orders (Guard may come in handy)
Yes, nothing says remove them.
c - features (like glyphs or unopened chests). If so, is the avatar disallowed to end move on a glyph ?
Yes, nothing says remove them and yes he is disallowed (avatar is still a monster).
2. There are several mentions of getting extra movement points "even when you wouldn't get any" (e.g. Elven Boots). Can you name such an occurrence, as opposed to "when you can't spend any" ?
Declaring a Battle action, or a Ready(Attack)