FEEDBACK: "Basic" Modern Browser functionality still missing from Edge...

leeuniverse 

(1) "Middle Tab Bar" (aka tab-bar above the page)

I'm not sure any browser does this anymore... even Firefox has them at the top, by-default.  Though with Firefox, you can probably find an "extension" to change this, as it's more-customisable than Edge.

(2) "Drag-and-drop text to search; or links to open them"

If you select text, you can right-click and choose the second item in the list: "Search the web for".

If you have two Edge windows open, and then drag a link from say the left-hand one onto the right-hand one, Edge will immediately go to that site.  I'm really not sure what the use-case is though for dragging a link inside the same window/tab and letting go to load that site... why not just click on it?

(3) "Forward and back history for that tab only"

You can do this: make sure the tab you want to see the history for is the one you're looking at (so click on that tab first, if needed). Then hold-down the mouse-button (or just right-click) on either the back or forward arrows on the toolbar.  It'll show you back or forward history for the currently-selected tab only in a list below.

(4) "Open a tab in the background"

The easiest way to do this right-now in Edge is simply middle-click on a link with your mouse: then it opens in the background, as a new tab.

(4) "Open new tabs right next-to the tab I'm on, not at the end of the tab bar"

When you middle-click a link, it will open next to the tab. If you middle-click multiple links, they appear in the order you clicked: 1, 2, 3. So the last one you click will be the furthest-away. If you'd rather the order be 3, 2, 1, where the most-recently clicked is always nearest, I'm sure the Edge team could implement that. Try requesting it via the "Send Feedback" feature inside Edge.

(5) Most-visited links UI

I just use bookmarks, so never bother with any sort of "start screen" so couldn't comment here.

(6) Option to re-open only specific tabs when Edge re-opens

There is an option in Edge currently called "Continue where you left off" which re-opens every tab when you start Edge.  If for some-reason one of the tabs has an issue, try to close it first before you close Edge.  Or if Edge crashes, try to close it before it has chance to load when you bring Edge back-up.

Though if a particular site is constantly crashing, you'd be better-off going to "Send Feedback", if it's a legitimate site, and advising there is an issue so the team can investigate it.  Or if it is a virus/malware site, go to "Report unsafe site" and report it there.  You'll find both options by going to the "..." option in the top-right, then "Help and feedback" at the bottom of the menu.