1. Yes, you can connect to those Node port services seamlessly.

But remember, you may need higher network bandwidth card and connection (to master nodes) if you get too much traffic to these services.

Also if you have a few master nodes, you can try dedicated master node-ip and nodeport for a service.(If you have 5 master nodes, each service is accessed from one master node's IP etc. This is not mandatory, you can connect to each service using any masterIP:nodeport)

Highly recommend to use load-balancer service for this. If you have baremetal cluster try using MetalLB.

Edit : (after Nagappa LM`s comment)

1. If its for QA, then no need to worry, but if they perform load test to all the services simultaneously could be a problematic.
2. Your code change means, only your k8 - deployment is changed, not Kubernetes service. k8 service is where you define nodeport