Certainly; a person running a fever will be hotter than normal, hence, both hot and feverish. There are, of course, other contexts and meanings of the word hot, which would not be synonymous with feverish. Angelina Jolie is hot.
You should try to avoid similar sentences. It's OK to use the word "it" twice if the sentences are different enough. Try to avoid passive sentences like "it was a stormy night" though. Instead, use active voice like "The night was stormy."
the difference between has and have is that you use has in sentences with : ( she , he and it ) for example : she has a book . but you use have in sentences with : ( I , you , we and they ) for example : you have a book , I have a book .
If you never use complex sentences, everything you write is going to be simple and you are limiting yourself in what you can do. You would find it hard to avoid using complex sentences if you are going to write a substantial piece of work.