For me, Google Docs works well. It's accessible anywhere, and it's easy to collaborate with others if you need feedback or have a writing partner. However, the best software really depends on your personal preferences and writing style.
The Lenovo ThinkPad is often recommended. It's durable, has a responsive keyboard, and provides reliable performance. Also, its battery life can last through long writing sessions without constantly needing to be charged.
It depends on the style and tone you want for your fiction. If you aim for a classic, timeless feel, past tense might be your choice. But if you want to draw the reader right into the action as it unfolds, present tense could be the way to go.