Hi,
My first suggestion is go with the bootstrap version (
https://demos.creative-tim.com/material-dashboard/examples/dashboard.html) it plays nicer with NetTalk, AngularJS tries to do stuff that NetTalk does for you already (and frankly much better).
To quickly and somewhat unhelpfully answer your questions:
Your question 1:
1. Create your own global pageheader. Place html into them that includes all the stuff above <div class="content"> (from the dashboard.html) - This is a gross over simplification, but its the starting point.
2. Create your own global pagefooter. Place html into them that includes all the stuff after the closing </div> from this <div class="content"> (from the dashboard.html).
3. Accept the fact that you'll have to do the menus yourself. Its the stuff in <div class="sidebar">.
4. Accept the fact that you'll have to do the top menu stuff yourself. Its the stuff in <nav class="navbar"...
5. You'll need to deal with conflicts, if any, between "creative tim" version of jquery etc with NetTalk. Usually a little bit of stuff, the general rule is change "creative-tim" not nettalk (NetTalk is far more powerful and complex - tim is just pretties).
Your question 2:
This could be fabulously complex... but I really like the style, so i might have a go with my own system and see how I go. The css is completely understandable, so will probably work.
Your question 3:
Possible now with NetTalk DIV layout mode, but I haven't tried for over a year, but its just bootstrap "col" layout.
Your question 4:
Just CSS, should work but you'll need to use the correct css classes within NT.
Your question 5:
Most of these will work, but they each depend upon your usage.
This all presupposes your a well skilled in NT,CSS,HTML,JS,JQuery and Bootstrap.
But it is possible see
http://www.nettalkcentral.com/forum/index.php?topic=8126.0 and
http://www.nettalkcentral.com/forum/index.php?topic=8127.0.
Regards
Bill Shields