Hello, Sadnesess, and welcome to the Grammar Exchange.
1. If you used this, it would mean..., In this sentence, does it mean that you don't use this now?
Yes, it means the other person doesn't usually use it, or is not using it now.
2. I want to write in great lenght to you, but I'm afraid I would be a bother to you this evening. Does it mean that in reality I don't write in great lenght right now?
3. "Will" would be used if the sentence wes real. I don't undertand the point here, does it mean the sentence is not real now? Am I right.
The correct spelling is "length," and the usual phrase is "at great length." It would be more usual to say "write a long letter / a long email."
The sentences above are not conditional sentences, but contain a verb in the conditional tense that could be expanded into a conditional sentence, for example:
- I would be a bother to you if I wrote you a long email this evening. (This means that I do not intend to write you a long email this evening.)
If I say:
- I will be a bother to you if I write you a long email this evening.
I also do not intend to write you a long email this evening, but I want to sound more categorical: if X happens, Y will happen for sure.
