Ask some questions about Mac purchase

Veterans, please help me see if you receive the goods 1. How to buy a Mac mini on Double Eleven? 2. Can beggar's version be basically developed? There are both mobile terminals and front-end terminals. It is not a large project. Do you need to add memory? (8G is 1.5 k, which is really expensive) 3. During the Double Eleven period, I plan to buy a Redmi 4K monitor. Is there anything for old irons to use this? I think it can be reduced by around 1k.