I have some probably dumb questions to ask about marxism and wasn’t sure where to go. Is there like a ask marxists or debate marxists forum? Anyway

You can post your questions on the "ask hexbear" and "ask lemmygrad" community.

What and how many branches of marxism want state socialism during the socialist transition period before Communism? I was under the impression that all (or most) leninists wanted state socialism during this period.

If by "state socialism" you mean "the revolution create a new state and uses it to protect the revolution" then Marxist-Leninists and "Maoists" want it.

I have since been told that Trotskyists don’t want this. Is this correct if so what do they want instead?

There isn't one specific thing all Trotskyists want, it's more of a customizable agglomerate of opinions centred around condemning everything the USSR or Stalin ever did and labelling every successful revolution revisionist while calling themselves Marxists. Trotskyists are what we call "ultras" (short for "ultra leftists"), they are dogmatists who think of Marxist political theory as an absolute checklist and will condemn every successful revolution for not achieving a to-the-letter identical system as was described in the books from the very second they came to power while, hilariously, often not having actually read the books and taking themselves part in the very historical and political revisionism they pretend to condemn.

How does this all relate to vanguardism?

Vanguardism is the idea that for a revolution to be successfull, there must be a political organisation harnessing popular drive for change and unify and guide it to form an actually pottent and organised movement with clear political goals so that it won't be easily crushed by the capitalist state(s) like often happen with spontaneous grassroot movements.

As for how it relate to your previous questions, it's in general the vanguard who create and take charge of the new proletarian state after the revolution.

Furthermore how does marxism define a state? Is this different from how other groups define statehood?

A state, to Marxists, is an instrument of class struggle, it is an ensemble of institutions with the purpose of keeping the dominated class under the authority of the ruling class through the use of it's monopoly on the lawful use of violence. Under a dictatorship of the bourgeoisie, like the United States, UK or France, the police and the legal framework is used to guaranty the right to private property for the ruling class and defeating and dispersing working class movements, this is why even peaceful protests for better wages or otherwise often face crushing police brutality that is never punished. Under capitalism you don't have the right to enjoy all the revenues your work generated, the legal institutions will make sure that you are forced to let your boss get a big cut out of it, thus guarantying the right to private property for him. Under a dictatorship of the proletariat on the other hand, the roles are reversed, the law enforcement this time guaranty that public property stay collectivised and that no one can extract surplus value from your work, they also keep the remnants of the bourgeoisie away from political power, with them often having to abandon their right to participate in the democratic process in exchange for their wealth. And of course, the bourgeoisie is also strictly forbidden to organise with the aim of re-establishing private property and capitalism.

It is different from how other groups define statehood in that other political frameworks ignore class struggle, to them, and to libertarians in particular, the state in and of itself is oppressive to everyone in general, they don't see that the reason the state we have in our liberal "democracies" is oppressive to most peoples is because it is welded by the bourgeoisie against everyone else, they see the state as it's own thing separated and isolated away from the broader society and think that even a state operated by the proletariat would necessarily oppress the proletariat.

I still don’t fully grasp the difference between marxists and anarchists. I thought the difference was mainly that anarchists don’t want a state, and encourage mutual aid. Now that I hear not all marxists want a state I am pretty confused.

Your initial thoughts were correct, the main difference between Marxists and Anarchists is that Marxists want a temporary proletarian state when Anarchists want to immediately abolish the state altogether. I don't know who told you that some Marxist don't want a state but that person was objectively wrong.