in general اِشْتَدَّ in this this sentence, you don't pronounce the letter "ا=a" ,, so it would be pronounced like "wshtadda behe...etc"

َتَــبَــيَّــن = a verb which means that something has been clear to you = became clear

:ِ) وإن كان المكان مكان جواب ولكني دفعني الفضول للسؤال : للإخوة المصريين, هل فعلا تلاقون "صعوبة" في فهمنا نحن في الخليج؟

in the first sentence the Tanwin is not part of the word.. it is something we add because of the location or position of the word in that sentence. in the example you gave, خبز was object , and since it is an object we will pronounce it with Fathah and we add tanwin because the word is نكره Nakerah,, which means that the word doesn't have " الـ THE " at before it but if there is الـ then the tanwin sound will be eliminated .. for example البنت تأكل الخبزَ the girl eats the bread ..AlKhubza .. NO Tawnwin I think the rule you wrote means that when you stop at the last word, there should not be tawniw sound, but if you continue the talk , you have to pronounce it (( I am not really sure about this point )) almost the same thing with the two examples the last two examples : 1/ I dont understand the pronunciation you gave, but I would pronounce it as Na'imah If itis the last word in my sentence but If will continue my sentence with some more details or any thing, then I would pronounce it as Na'imaton 2/ this has to do with something called " الممنوع من الصرف " which means that some words are prohibited or prevented from having Tanwin.. and Kasrah (" It could be pronounced with Kasrah in cases like if it is added to a word after it or "الـ THe " has been added to it )) this rule is more complicated and you have to have some more basic rules to understand it there are a lot people who are native in Arabic haven't heard about this rule.. and even if they did, they still don't know how it works :)