Not only the reward for running a service node is in future the money.
If you offer exchange service on your node you earn fees.
This is much more as the reward for running a servicenode.
For the exchange service 5000 coins are needed?
Yes you need 5000 Coins for Servicenode.
You can start the Servicenode as simple Node or as exchange.
For Exchange Modus you have to install the Wallet of Coins which will you deal.
is there a benefit to running an exchange node over a simple node?
You get to share in the trading fees too. 70/30 for node/stakers. Imagine if the the blocknet DEX starts picking up in huge volumes... $$$