If you had the importunity to reboot the Marvel Universe (616) from scratch, would you? What kind of things would you change? Would they be drastic? What titles would you like to see come out of it, and how would you end the current continuity?

No. 
 
The idea is stupid. 
 
Although making a new, less "edgy" ultimate U might be nice.  But NOT A REBOOT.

I think if the DC reboot is successful than Marvel will definitely follow suit, 
 
I really can't speculate on the changes as I haven't really seen what sort of "changes" DC has made, For one thing as X-Men being my favorite comic title I would like to see a reboot of theirs be less convoluted and migraine inducing...
 
I remember when first having access to the vastness of the internet trying to read up on Jean Grey and Madelyne Pryor,and things like Siege Perilous, Magiks ordeal, and feeling like my brain was going to bleed

Get rid of everything that has happened since Civil War. I'd have had the Annihilation Wave come in and Nova verbally beat down the MU heroes like in the What If? Issue.

If it were up to me, I'd have Scarlet Witch come back, and warp reality for good. Not like House of M where the heroes knew what's up, I mean a full on reality warp.  
 
I would revamp some origins (Captain America's, Iron Man's, Hulk's, and the X-Men's to name a few), definitely get some new costumes for most of them, and put each hero on the team that they should be on (Wolverine as a full on X-Man, Steve Rogers is a full on Avenger, and  Spider-Man, Luke Cage, and Daredevil are on a Marvel Knights team). 
 
I wouldn't start from the beginning. I'd start from after Civil War/Annihilation, but the outcome would've been different. Events like Secret War, Secret Wars, Kree/Skrull War, etc. still happened. At the beginning of each comic title, there will be a short retelling of the characters' origin.  
 
This would be my 52 titles: 
 

1.        Avengers (Slott) – Captain America, Iron Man, Thor, Ms. Marvel, Hawkeye, Spider-Woman, and Red Hulk take on the biggest threats as Earth’s Mightiest Heroes.

2.        Avengers: Black Ops (Brubaker) - USAgent, War Machine, Moon Knight, Noh-Varr, Mockingbird, Ant-Man, and Black Widow take on potential threats as a secret team that takes no prisoners.

3.        Young Avengers (Heinberg)- Patriot, Vision, Wikkan, Hulkling, Stature, Speed, and Hawkeye make up this teen super-group.

4.        Avengers Academy- (Gage) Hank Pym, Justice, Firestar, Tigra, Quicksilver, and Jocasta are the instructors of tomorrow’s superheroes.

5.        Captain America (Brubaker)

6.        Invincible Iron Man (Fraction)

7.        The Mighty Thor (JMS)

8.        The Incredible Hulk (Pak)- Starring Bruce Banner

9.        The Fantastic Four (Hickman)

10.    The Amazing Spider-Man (Slott)- Mainstream Spider-Man

11.    The Spectacular Spider-Man (Bendis)- Peter’s high school years

12.    Daredevil: Man Without Fear (Bendis)

13.    Dr. Strange: Sorcerer Supreme (Waid)

14.    Ghost Rider: Spirit of Vengeance (Williams)

15.    Moon Knight (Bendis)

16.    Elektra (Diggle)

17.    Cage and Jewel (Bendis)

18.    The Immortal Iron Fist (Brubaker)

19.    Heroes 4 Hire (Brubaker)- Power Man, Shang-Chi, Dan Ketch, Misty Knight, Black Cat, and Echo at your service.

20.    Marvel Knights (Benids)- Daredevil, Spider-Man, Wolverine, Cage, Iron Fist, and Black Widow fight crime on the mean streets of New York.

21.    X-Men (Morrison)- Cyclops, Wolverine, Emma Frost, Beast, and Namor deal with mutant-human relations

22.    Uncanny X-Men (Jenkins) Magneto, Iceman, Rogue, Gambit, and Sunfire protect and serve mutantkind

23.    Astonishing X-Men (Whedon) Storm, Angel, Colossus, Nightcrawler, Shadowcat, and Psylocke deal with non-mutant threats to humanity

24.    Class of X (Gage) Prof. X, Darwin, Havok, and Polaris coach the next generation of X-Men.

25.    Uncanny X-Force (Remender) Wolverine, Angel, Psylocke, Deadpool, and Phantomex seek and destroy all threats to mutantkind.

26.    X-Factor Inc. (David) Madrox, Layla Miller, M, Strong Guy, Longshot, Sirin and Wolfsbane are criminal investigators in New York City.

27.    X-23 (Liu)

28.    Thunderbolts (Ellis)- Songbird leads them  

29.    The Punisher (Ennis)

30.    Namor the Submariner (Cherniss)

31.    The Silver Surfer (JMS)

32.    Annihiliators (Lanning)

33.    Nova (Abnett)

34.    USAgent (Brubaker)- When Bucky Barnes reestablishes himself as a hero, he ditches the Winter Soldier identity and becomes the new USAgent.

35.    War Machine (Fraction)

36.    Red Hulk (Parker)

37.    Black Panther (Hudlin)- Starring T’Challa

38.    Wolverine (Millar)

39.    Deadpool (Way)

40.    The Inhumans (Hickman)

41.    The Raft (Ellis)- Alook into SHIELD’s high-tech security prison and its deadliest inmates

42.    Nick Fury: Agent of S.H.I.E.L.D. (Brubaker)- Fury is back as the director of the Strategic Homeland Intervention Espionage Logistics Directorate; SHIELD.

43.    Power Pack (Heinberg)

44.    The New Invaders (Waid)- Steve Rogers, Bucky Barnes, Human Torch, Toro, and Namor the Submariner are together again since WWII to fight the good fight (also goes back in time for past Invaders stories)

45.    S.W.O.R.D. (Whedon)- Starring Abigail Brand

46.    Doom (Brubaker)- Starring Dr. Victor Von Doom

47.    Venom (Remender)- Starring Eddie Brock

48.    Ms. Marvel (Waid)

49.    Captain Marvel (Ellis)- Starring Noh-Varr

50.    Alpha Flight (Van Lente)

51.    Marvel Comics Spotlight (Various)- A testing ground for creative teams and superheroes (or villains) that do not have their own titles (Sentry, Black Widow, etc.)

52.    Journey Into Mystery (Various)- A look into our heroes’ and villains’ past as older stories are retold