A rattle is a child's toy. It's something that is made up of a few loosely attached parts. You shake it and it makes rattling sound - it rattles - hence the name rattle.

I've been told by some native Spanish speakers that confusing b and v in writing is quite common. It's not unusual to see móvil spelled as móbil, for example (I'm not sure why it's spelt móvil actually. Maybe someone can explain it. It seems strange to me to use v rather than b in this case).

The phrase is commonly used idomatically as "to each his own", it's sort of a set phrase. There's no reason you couldn't use "to each her own" as an equivalent saying. It might sound a little odd because we're so used to hearing it with "his" but I wouldn't think much of it. It's also very common to hear "to each their own" which is more inclusive and avoids the use of gender.

I agree it's a tricky one. I think I would say it's not given. It only states that the steam ships could (were able to) use the canal while sailing ships couldn't (were not able). This is about what the sailing ships couldn't do more than all of the things the steam ships could do. It doesn't actually say whether they used the ocean route as well anywhere in the text. However, it also says they were a growing threat to sailing ships as a precursor to the canal being built. This implies that they were already in increasing use. Before the canal existed they had to get there somehow. Probably via the ocean? It's not explicitly stated though, so personally I'd still say "not given".

The commas are used here to offset a non essential part of the sentence. "Think ahead" is a clarification of what they mean by "look ahead". The sentence is still understandable without it but it emphasises what they mean. You could say: - People need to look ahead and think ahead. Although probably more common is: - People need to look and think ahead (avoids repetition). But it changes the emphasis in the sentence a bit. Instead of being "look ahead" + some clarification of what they mean, you have "look and think ahead" and it changes the flow, or "punchy" point making of the sentence. I'm probably not explaining this well; it's a stylistic choice that conveys its meaning in a certain way that I am finding hard to describe. It has a sort of urgency in the way it's written.

Both are fine and commonly used (in the UK at least). They are interchangeable.

You will be understood but semantically it doesn't make sense. Essential is absolute, it can't be compared. It is either essential or not essential / nonessential / inessential / unessential. If you worked for a newspaper your editor wouldn't allow it. Importance is relative, some things are, or can be, more important than others. They are not absolute, they are comparitive. Short answer: You might hear people say and it's understandable, but technically incorrect. I suggest comparing with important instead.

I think you mean "foul revolt". Foul means disgusting, wicked or immoral. A revolt is a rebellion against a regime, government, authority, etc. So it means the disgusting betrayed that they made against God. It also wouldn't surprise me if - this being Milton - revolt was a carefully chosen word here, as it can also mean to feel disgust. There will be loads of resources online for Paradise lost. It's an extensively studied book. Do searches for (paradise lost notes / discussions / explanations / reading guides / etc). It's very hard work to read and is not usually studied until university level English in this country. I'm not saying don't read it but the concepts, parody, unexplained references and interpretation alone make it difficult. The old style of writing can be confusing to native speakers as well, so make sure you're very comfortable with your English before you take it on or I expect it will be very frustrating.