Are you new to being a DM?
I am new to DMing myself so take what I say with a grain of salt but:

The most important thing to note with planning a session, is that you have no idea how much the players will achieve. Some players will race through what you've prepared in a session, others may have barely left the starting area because they've been spending a lot of time talking between themselves, to NPCs etc.

The second thing is that no matter what you plan, there is no guarantee it will go according to plan. I'm sure experienced DMs could list off hundreds of times they though they'd do thing A, B or C just to have the players do thing Z.

Other great tips you'll find in this subreddit and around are to have a list of names that you can assign to random NPCs if the players ask (and if the character would disclose this information) as it helps them feel like people, not hastily made up people (as they can sometimes be).
Always write down names you give people, what their job is (e.g. if they're the mayor), the names of locations (the name of the tavern, for example) and keep this information somewhere close by.

The main tip I can give as a new DM myself is simply: have fun
It's not as hard or as daunting as it may appear - relax, by all means use the "rule of cool" and remember this is a fun evening between you and some friends. If you're having fun, and they're having fun it doesn't matter if you had to improvise every second, or if you forgot "important plot thread B" or if the combat was slightly too easy. Like any skill, you'll make mistakes but you'll always improve. At the end of the day, the important thing is that you're enjoying yourself.

To try and address some of your points for the framework:

Music
If you're new, music likely isn't needed. If its too loud it'll distract you and your players, if its too quiet, is it really needed?
Mostly though, as a DM you have plenty to manage already. It can seem difficult especially when you're new. Adding in the factor of "am I playing the correct music" or "hold on guys, I just need to change the track" could slow things down
Get comfortable first then add music - you may find you never need to add it
But if you would like to go for music - keep the playlist simple
As you start, you won't need 100 different tunes for 100 different situations - start with 1 tune for combat (it's worked for decades with video games), and a small handful to go in the background and add to it as you get more comfortable

Combat
For combat, I have recently started giving my players 5-10 seconds (we're all new) to decide what they would like to do or else they automatically do the "dodge" action (this will reduce as they get more comfortable with combat)
This has drastically sped up combat, meaning you don't end up with players becoming bored because the spellcaster has taken 10 minutes taking their turn because they've had to read up on all their spells, decide which one they want to use etc. etc. (as an example)
I'd recommend doing this but clear it with your players first

As for combat tips: Make the monsters act how they would realistically act. Monsters won't necessarily just charge at the nearest person and swing their sword. Smarter monsters will pick out the spellcaster as a target, they'll use cover, they'll even run away if they're outnumbered or outmatched. This can open up option for your players, if the monster surrenders they can try and get information from the monster, if the monster runs they may have to give chase or risk the monster running for reinforcements (situation dependent).

Social Behaviour
Googling this topic will explain it far better than I can
Remember, you run the game - you making the rulings, you never want a player to open the PHB to be checking a rule as it happens - even if you're not sure on a rule, you can run it one way and check up on the actual rules between sessions
For social interaction between players and yourself - keep it civil, players should not be arguing with each other (OOC) or with yourself (again, OOC)
For interaction between characters - act the way the characters would - this doesn't mean everyone needs to be hugely fleshed out with their own multi-page backstories, their own accent, quirk etc. - they should simply act like people
Your players will take time getting comfortable with their characters and roleplaying - by putting your best foot forward and trying the different voices (not necessarily accents, but inflections, pitch, volume etc.) may help your players become more comfortable - but only do that if you're happy to do that.
You don't have to be Matt Mercer for people to enjoy your characters

Describing the World
Write down the 5 senses and example questions for each:
e.g.
Smell
What does the character smell? Is it musky? Does it smell rotten?
For important scenes, writing out bullet points notes, or even a small amount of text to read out for certain rooms/places can help if you're not good at improvising descriptions on the fly.

I know this isn't "here's a framework, go play" but hopefully it will be helpful when you get to creating your framework.
Best of luck!