Almost all Lit. teachers are/were English teachers too, so they're likely to know just as much as your actual English teacher. If your Lit teacher is just a better communicator, then I'd definitely have a chat to her about any English troubles you're having.
I actually did the opposite when I was in Year 12; my then English teacher was my Lit. teacher in Year 11, and I found his insights way more helpful than my actual Year 12 Lit. teacher. But I didn't just want to bombard him with Lit essays, so I tended to just organise a time to see him and talk about English, then subtly transition over to Lit

So in your case, you could perhaps chat with your Lit teacher about the difference between a Passage Analysis and a Text Response (eg. 'hey miss, I don't really understand the difference between what a Lit. topic sentence should look like, as opposed to a Text Response one...')
Considering most students are more familiar with English than Lit, I'd imagine your Lit teacher would be fairly used to having to explain the key differences between the two subjects, so it wouldn't be too much of an imposition, I'd say.
Essay marking is a little different. It's really just dependent on the dynamic you have with your teacher. It's possible that your English teacher is just incredibly busy, or gets swamped with emails from other students (especially since you said you tend to send him essays before SACs) so in terms of getting feedback - try and organise a time to talk to him so that you can get him to give more detail (ie. rather than just reading his comments that say vague things like 'make topic sentences better,' you can actually ask him 'how would I do that?' or 'what is it that's making my current ones weak?' or 'do you have any examples of this done well?')
The other possibility is that they're just not a good teacher. Some teachers are just incapable of helping either because they don't know the answers themselves, or they lack the ability to communicate such answers. You shouldn't assume this is the case just yet, but in the event your teacher is unable to give you any guidance after you've spoken to him, then you'll almost definitely need to seek assistance elsewhere.
Out of curiosity, do you find your English teacher helpful in class? As in, are his explanations or discussion questions useful for you? That might give you some indication as to whether it's worth trying to get his input, or whether you're better off checking with your Lit. teacher instead.