MathML Vector representation issues

First, I should say that I am delighted with MathML, and its achievement!
It is great and much needed work. However, as a complete newbie to this
subject, I joined this group out of frustration with the inadequate html
mathematics representation abilities, specifically vector representations.
Vectors are a basic mathematics subject, as basic as it gets, and extends
to physics and engineering. However, even the most basic representation of
a vector seems missing in HTML and greatly missing in the prevalent
browsers except in Firefox. I have these questions:
1. How do you display the vector "a" as a single UTF_8 character, (an arrow
on top of a letter)? All the browsers showed a shifted arrow not top
centered.
2. using MathML, and  <mover> or <munder> works, but for a full string, it
only works on firefox, and fails miserably on Chrome and Edge.

HTML provides text-decoration: overline, which allows placing a Bar above
or below a character or set of characters, but not an arrow (vector). How
was this missed and not included as an option. It is a sad omission.

3. Finally, not having in HTML and maybe MathML ability to specify location
relative to the base in all 9 directions: as {top or above, below or under,
left, right, topright, topleft, bottomright, bottomleft, center} seems like
an omission that needs to be addressed ASAP, unless as a newbie, I am
missing something. This item 3, by itself, when linked to the numeric pad,
or a virtual keyboard, allows all the freedom a mathematician needs to
write and edit equations with great easy.

I joined this group to relay this concern, and shortly, I will leave it as
beyond my expertise. Many many many thanks to all the great contributions
your groups have done to facilitate math access.

Jamil