Depends on the novel. First person perspective (我): Present tense Third person perspective (他/她) : Past tense This site might be helpful.
Present tense is trickier and more prone to errors if you're not careful/doesn't have much experience reading and writing in present tense correctly. Past tense is more recommended. Arguably easier to do and since a lot of stories you can find are written in past tense, it's more natural
Depends on the grammar system you want to follow when translating, English grammar, or Chinese one. If you choose to follow English grammar, I believe that NorthBladeTL and meliori's answers are good enough. If you choose to follow Chinese grammar, you must know a little about Chinese grammar. Normally, Chinese author writes their story in the present tense and doesn't depend on points of view in most cases. If you find one of those words below in a sentence, that means the sentence written in the past tense: - "过", "曾", "前", "的时候", "没", etc. - "了" in some cases; - Time words in the past, such as "昨天", "上个月", "以前", "去年", etc. There have more ways to recognize the past tense in Chinese grammar, you will know them after reading a few Chinese novels. I hope this answer will help you.