Need some questions answered. Preferably by comic book readers.

I will take a stab at your questions, however its been a long time since I was comic book reader.

1st question : The simple answer is, it was more for comedic value than anything else. Comic Loki has always had the ability of teleportation so the comic Loki would have escaped without a problem, movie Loki is a bit more sketchy on his full range of powers, maybe it would work, but I suspect he would find his way out one way or another. Thanos it would be an interesting idea, however, he already controlled several of the stones when Strange first met him (4 at that time I think) Reality stone alone would make it impossible to stop Thanos in this fashion. It DOES however give a perfect way of dealing with a rampaging Hulk.

2nd question : Thanos is not easily harmed in the comic or the movies. I doubt Iron Man had anything on him that would cut through his arm quickly, and once he starts feeling that pain he would awake from Mantis' control. Of course you could make the argument that Tony wouldn't have any idea how difficult it would be to cut through Thanos' arm, so it came down to making a judgement call.

3rd question : I have no idea, and I feel the same way you did. He showed nowhere near the power I was expecting from him.

Hulk is a writer's choice, I'm interested to see where they go with it. From the comic's there have been a handful of times where Banner had trouble changing. I think in Ultimate Avengers, he was on a drug of some kind that kept him from turning. Cap. America had to kick him out of a helicopter to get him to change.

#1: Thanos had the Space Stone and with it, he can open portals to other worlds. He could pop right back onto the battle field.

#2: Strange could have teleported his arm off and Thor could have chopped his arm off using Stormbreaker. I think the only explanation is because the plot needed him to stick around. The comic version of Thanos is insanely hard to hurt even without the Infinity Gauntlet but this version seems like he could be cut.

#3: He had a huge spear go through him. That's going to stop him from doing too much. Even then, he still managed to survive for a long time and even fight to some degree.

Well, I'll chime in. But really, the answer to all this is "Because the story dictated it".

1) You can say either a) Stranges magic is different than Asgardian magic and Loki could not counter it easily. OR, Loki had no idea where he WAS so could not easily do a teleportation since he didn't know his starting point.

2) Thanos is FAR more powerful than a simple laser. And that's even in his lesser powered movie version. In the comics, he fought off the Avengers (including Iron Man and Thor and Vision), the Thing, Spider-Man and Captain Marvel SIMULTANEOUSLY and would have won if Adam Warlock had not reappeared out of the soul gem. And that was without the gauntlet.

3) Ah, Vision. He has a long and storied career of getting jobbed to make the bad guy look tough. He has almost spent more time disassembled than he has fighting. Plus, as others have said, they showed and told that the first stab of that spear/sword thing screwed up his phasing ability.

Good questions all around. My answers in short:

1. Thanos was wearing the Infinity Gauntlet with the power stone, space stone and soul stone. I know that Doctor Strange is a powerful wizard but the Infinity Stones have been around since creation and are each extremely powerful on their own. With the space stone, Thanos could have simply teleported from any time/space hole Strange could cast him into.

2. No answer except that Tony/Iron Man is one of the "good guys" and isn't going to severely injure a being if he can help it. Also again, Thanos is an Eternal, which are a race of very powerful beings created by the Celestials. If Ebony Maw kneels to Thanos (and consider Ebony Maw's power), then Thanos is truly scary strong. He might not be so easy to injure.

3. Vision's biggest issue is his thirst for humanity. He knows he is super-powerful, perhaps one of the most powerful beings on the planet but he's still understanding this power, like a child learning to control a flame from a lighter. He even tells Wanda in Civil War "You know, I don't know what this is or what it does," when referring to the mind stone in his head. I think he's more hesitant to use his full powers, simply because he doesn't understand his full powers.

Anyway, those are my answers off the top of my head. Good questions!

Absolutely right
All those are plot contrivances