In Android, how do I choose specific sites to go in my new team page and stop it adding useless link?

I recently switched to Firefox on Android from Chrome for obvious reasons. It's great! Except the new tab page is a piece of shit. I've already disabled all the sponsor rubbish and stuff*, I want to choose specific links to put there and stop it from adding links to random places I happen to visit that I can't get rid of without removing it from my history. Why this behaves like this is beyond me. I should be able to SET my shortcuts, not have to rely on Firefox to hopefully pick the right ones for me and then have to put up with every other one it decides to add or wipe them from my history.

*Why are these options so poor? I don't want recent bookmarks on this page, I want the ones I've used the most, which will have been bookmarked the longest. Recently visited? "Hey do you wanna return to that one Google search from a day ago?" Why!?

Whilst I'm here, can I change tabs to work like Chrome. I.e. currently on Firefox when I'm on the new tab page, and I click a shortcut, it then opens a tab, pressing back goes back to the new tab page but leaves the tab open in the background rather than closing it.

The new tab page should be part of the new tab, hence the name, so when I press back I should still be in that tab, but back to the new tab page, and without any tabs open in the background that I now have to go and close myself. If I don't choose them, next time I go to that site by pressing the shortcut, it'll open the already loaded tab instead, forcing me to refresh it manually and adding a superfluous step for literally no rational reason I can think of. Firefox seems to act like a tab is launched from the new tab page, rather than the new tab page is the first page you see in a new tab.

I hate these behaviours, they don't make sense, so thanks in advance for at least trying to fix them for me.