I was wondering how and where the pixel code gets added to our shopify store. What specific code is added and where?

Attribuly pixel is automatically installed via Shopify API, it looks like this:

https://data.api.attribuly.com/v2-1/<your store ID>-dm.js

You might search " attribuly" in your webisite's source code to get the snippet.

Any impact if I update with Attribuly UTM template?

Facebook & Google will review the changes, normally it take several minutes to 1 hour. The ads are keep running, the ads id are all the same.
Your currently UTM template stay unchanged, because Attribuly UTM will have no confilct with it. There is no change for any tools receiving data with your existing UTMs.

Can I generate UTM links in bulk?
To generate bulk links or short links, you may use 3rd party UTM builder such us Terminus. Make sure you follow the stand UTM structure.

For short link, Attribuly pixel is also able to capture the parameters.

For influencer link, make sure you put " UTM_medium=influencer" in the link.

What is the advantage of this side compared to Google Analytics(GA)?

Please see the dedicated article: https://attribuly.com/blogs/how-to/compare-attributly-with-google-analytics-4-attribution

Can all ads be tracked to the ad level, such as the AD level of Google ads?

Yes

How are new customers defined for ncROAS?

Within the selected time range, users who have never placed an order before are defined as new customers.

Does UTM used to track ads?

Yes, we have our own UTM template that does not conflict with your company’s and can coexist to mark ads.

How can Attribuly better evaluate effectiveness for branding ads?

Previously, for example, Google Ads used last-click attribution, which actually erased upper-funnel ads contribution. Therefore, we recommend trying multi-touch attribution models + longer attribution time windows, which can allow us to see the conversions brought by branding ads and are more effective for brands. We will accurately allocate conversions to different types of ads, making it easier to evaluate the value of display ads.