1. dreary, dismally, failing, dim -> atmosphere of gloom, darkness, depression
2a. breathless, unable to sleep, tiredness, cold sweat, teeth chattered, every limb was tense
2b. anxiety, horror, disgust, disturbed by the wildest dreams
The weather reflects Frankenstein's feelings of exhaustion and horror because it's dark and depressing.
3. The light may represent the failure of Frankenstein's morality and sense of responsibility for his monster. This might tell us that the writer disapproves of Frankenstein's experiment.
4. lifeless thing, the creature, the (terrible) wretch, the being, the (miserable) monster. Frankenstein uses the pronouns 'he' and 'it' to refer to the monster. The use of 'he' implies that he sees the monster as human to some extent but 'it 'implies that he sees the monsters as somehow less than human at the same time.
5. eyes: dull, yellow, watery - teeth: pearly whiteness - hair: black and flowing - skin/complexion: yellow, shrivelled, black lips.
This creates an impression of horror, illness and death.
6. The creature watches Frankenstein while he sleeps; it tries to communicate, but it is inarticulate; it stretches out its hands to Frankenstein; it smiles at Frankenstein.
7. Your own answers.