I am using Ubuntu and am wondering if installing Snort on my host can make me more vulnerable?
Any software you install on your machine that takes input from other machines you do not control makes you more vulnerable.
You must balance the additional risk you add by installing Snort against the costs of any treatment for that risk you might implement and the benefits of installing it.
We can't do that for you because we don't know your threat model or why you want to install Snort.
Yes. But with the latest and greatest version, perhaps not so much that I would worry about it in your case.
You can always google 'snort vulnerabilities' and note that most really bad known exploits relate to old versions. That is a pattern you'll see often.
For protecting your home computer:
Not necessary in that order..
Snort is great, but depending on your background it's possible you should start somewhere else. And definitely use third-party software vs Snort.