Where to start with Crypto fees

I have spent some time using simulators, and it’s been okay. I would like to start with small amounts in the real world. My question is:

1. What commissions or fees apply if I want to trade cryptocurrencies like Solana (SOL), Ethereum (ETH), etc.? Are commissions applied only when withdrawing funds, or are they applied to each transaction?
2. What are the best trading platforms for someone based in Europe?
3. I plan to make around 10-20 transactions per day (scalping) since I don’t have a large budget. What should I consider to minimize costs and optimize trading?

Your help would be greatly appreciated!