Specify each one of your problems so we can help you better. As for "when to present a character" is quiet hard to tell without knowing how things are going, I think the only way I can answer such a vague problem is with a vague answer: just go with the flow of the events.
I personally have no technique or strategy in writing, which is weird because I try to read a lot about narrative theory, but it's maybe because I haven't made anything finished yet and I mostly pass the time understanding how other writers over come their problems. So I can't help you in my personal experiense.
I disagree with you that anime is better than manga. This is because your statement is equal than saying "fish is better than apples", it doesn't make any sense because you are comparing 2 different mediums. The whole narrative between a comic and a animation are too different to compare, but to tell you the true, most anime made from mangas are crap just for the fact that they don't take advantage of the narrative of their own medium but get stocked in the narrative of the source medium, which is a failure, because you are just replicating the comic with a "sense" of animation. And obviously they are just replicating the dialogues, making the anime a copy paste of the source and not a production in its own. But this debate is better to another thread, not here, so I'm not going to reply about this.