Your exhaust won't hurt anything.
As far as monitoring think of it as cheap insurance. Gauges help you know if something is starting to go bad before it goes. These things may not always be apparent to a driver no matter how long they've been driving or wrenching. How would you know if your uppipes are starting to leak, HPO is getting weak, you have low fuel pressure or a small boost leak? Thats where gauges come in handy to show you if something small is wrong before it becomes something big.
I used to never run gauges on my trucks but ever since I started using them I won't run any diesel truck -stock or not - without at least boost, EGT and tranny gauges (or an all-in-one monitor). By having gauges I've found when I've had boost leaks and a fuel pump going out before they caused issues.
Do you have to have gauges? No. Are they a good idea and a smart investment? Yes. A good gauge setup will run you ~$500 all said and done for trans, boost, EGT, mount pod, and misc stuff depending on brand and style.
Plus if you come onto a site and start posting questions about why this is/is not happening the first thing people are going to ask is what was your _____ gauge reading and if you say you don't have _____ gauge your going to hear "get one put in then get back to us". Same goes for a code puller of some sort - heck even a cheap auto store one is better than nothing. It all helps you in the end.