What is the best way to deploy and test smart contracts on multiple machines?

You can have a small private network of 2 or 3 nodes, for example using docker-compose.

There are a lots of tutorials out these explaining how to make sure that your nodes are connecting to each others, by passing the addresses explicitly.

If you don't like Docker, here is an example of how I setup a private net of 2 geth nodes using a Makefile: https://github.com/WeTrustPlatform/poa-interchain-node/blob/develop/dev/Makefile

Now what you want to achieve with monitoring events is a very common use case. There are APIs in multiple languages to subscribe to these events, or list the past events.

But as @goodvibration said in his comment, you may as well have multiple process talking to a single node, because events will be pushed to your listener when the block is mined, so having multiple nodes is useless.

I would go even further and say that if your information system rely on Ethereum, and you want to avoid sync issues, you'd better have all your services pointing to the same RPC endpoint. It's a very common source of UI bugs, when people have their client connected to let say infura.io, and their server to a hosted geth node, if the two nodes are a bit out of sync your system will have to handle that. By using a single endpoint you avoid a lot of complexity.