So let's assume I don't care about energy consumption and mining the famous reward for discovered block. Is it possible to set up a workstation optimized to harvest just the transaction fees? Do I need to participate in a pool and run mining software?
No, it doesn't work like that. The fee for a transaction can only be collected by a miner who creates a block including the transaction. Creating a block also entitles a miner to collect the "famous" block reward (they could decline to collect it, but that would be stupid). There is no easier way to collect transaction fees; you have to mine like any other miner (either solo or in a pool), and at least for Bitcoin, you can't economically do that with ordinary computer workstations.