Avocado

I found a market near my place that sells fresh avocado and i love it so i thought of buying a lot and store them in the fridge but I never "owned" avocado so I need some advice...

- How much will an avocado last in my fridge?
- Can I pre-peel and cut them and store them in a tupper-ware in the fridge?
- Should I buy them when they are hard to touch or when they are slightly 'bland'?
- if I put them in my bento will they get brown? Should I wash them with lemon juice first?

any bento-friendly recipe involving avocado will be VERY welcome! ^^

Thanks in advance! ^^