...do I write about myself in the 3rd person or not?
As said before. What is the service, are you a one man operation, and are you trying to project as a company? If you're a company, then you can either identify yourself as the writer when needed and speak directly to the viewer, or you can go completely 3rd person as it is the firm speaking.
If you're a one man shop and trying to be you, and not a firm, selling services, then its a conversation between you and the reader.
Depends. First of all what kind of service?
I'm 25, and I appreciate it when I'm dealing with businesses that isn't afraid to show personality and a sense of humor. The mailchimp branding comes to mind. I like to know that when I send an email to the owner of the site, he's responding. An older generation might find more comfort feeling your business is established with a more corporate feel. Again, your industry will influence tone of voice for your content quite a bit.
If your audience will feel more comfortable thinking your team is bigger than it really is, use "we".
Straight up talking in the 3rd person is cheesy. Everybody knows you wrote your own content. However it might be appropriate in an extremely academic autobiography for a lawyer, therapist, or someone with a PhD. When talking about your services talk TO your audience and about how you can help them accomplish their goals, not a lesson in your business plan.
The most important thing you can do is contemplate exactly who your audience is - did they come to your website to do research, or do they already know exactly what they want? Accommodate them. Make it easy.
Thanks for your insight, 1st person it is. Now, I just need to figure out what to write.
Best bet is to write in the second person. Weird, I know. "You can get this, you can have that. You will have this.
Nobody really cares about YOU. They care about what they can get, what problems you can solve, what hairballs they can get untangled.