What difference does it make if I use "Добрыи" instead of "Добрый"?
Добрыи is incorrect, добрый is correct. :) It might be similar, just like "like" and "ljke", but only one is correct, and another is not.
Please note than и and й are different letters, just like i and j. In the past, й was a variant of и and j was a variant of i, but that was long ago. Now they are completely different letters (both и/й and i/j).
[Of course, this only applies to modern languages. In Latin, j is still a variant of i. In Church Slavonic, й is still a variant of и.]
ь changes the pronounciation of the previous consonant, it makes it 'soft'. Usually softness is shown by the vowel letter (e.g. soft н before а is shown by ня /nʲa/), but if a soft consonant is not followed by a vowel, then you use ь.
Я, е, ё, ю have a double use:
- after vowels and at the beginning of the words, they show a vowel preceded by /j/: я /ja/.
- after consonants, they change a pronunciation of the consonant: ся /sʲa/, ля /lʲa/, мя /mʲa/.
When И follows a consonant, it also makes it soft: си /sʲi/. However, at the beginning of the words and after vowels it makes a plain vowel: и /i/.
ъ is used only after some prefixes, when a hard consonant precedes a /j/ + vowel. For example, съесть /sjestʲ/. It shows that е shouldn't make /s/ soft.
This is a vowel sound that doesn't exist in English, similar to Turkish ı. It never follows soft vowels.
Dimitri is the anglicised version of the old version of the name, Дими́трий. I don’t think it’s used for modern people either in Russian or in English.
Demitri is not correct. But a lot of no Russian speaking cannot speak my name correctly :) Because letters ДМ together is so difficult for them. So it is not trouble if someone will use some kind of option of pronounce of my name :) And also writing Дмитрий: Dmitry, Dmitrii, Dmitriy are possible :)
I don't think it is. For me, «ве́чер» begins roughly at sunset (maybe a bit eariler, but anyway, the time when it gets darker) and ends either when it gets maximum dark, or when you go to bed.
When talking about time, 4 pm sounds strange with «четыре часа вечера», only with «четыре часа дня». 5 pm sounds OK with both («пять часов вечера» or «пять часов дня»). 6 pm sounds much better with «шесть часов вечера», but sounds strange with «шесть часов дня».
We don't have a direct correspondence to 'afternoon', but «день» often works as a translation. Since Russian has the word «сутки» '24-hour period', «день» is much more often used for the bright period of the day than for 24-hour period. (However, де́нь begins earlier than 'afternoon'.)
I think that depends on the person. Probably, not many people say «четыре часа вечера» (it doesn't sound bad to me, though), but in the theory it wouldn't be wrong to say that «ве́чер» starts after the noon. Nobody says «время после полудня» to refer to the afternoon; that's just too long to say.
It also depends on the situation. If you refer to the afternoon in general, you can say «после обеда» (e.g.: I am going to rest in the afternoon = Я отдохну после обеда). But, if you refer to a concrete hour (4 o'clock in the afternoon), you don't say «четыре часа после обеда / после полудня».
I agree with you in saying «четыре часа дня». It sounds much better. What I am trying to say is that, in the theory, «ве́чер» could be both used for evening and afternoon, but in the practice the language is more flexible.