How best to track the successes of a flow campaign

You can run a smart list, look at the members by week tab on the campaign, or run a Lead Performance Report that looks at activity this week. (might require some work).

You might also try using a Campaign Performance Report. You can choose which campaigns to include in the Setup tab, and which leads you want to contribute to the report in the Smart List tab.

When you say "what pieces they engage/not engage with," I'm guessing you mean emails and landing pages. To make this easier, I would put the emails and landing pages the campaign uses inside the same program. You can then set up one of each of the Landing Page Performance and Email Performance reports that focus within that program.

Within each report, go to the Setup tab, drag in a filter from the right and check the box next to the program:



This will make it so that you report on all the assets in that program of the type the report is for (landing pages or emails).

Narrowing it to leads added to the campaign in the last week is a bit trickier. Since you're pulling them from SFDC, if they're new leads, you can use a Lead was Created filter in the report's smart list with a date constraint of the last week. Otherwise, if you change some lead field when they are added to the campaign, you can use a Data Value Changed filter to accomplish this. Whatever you end up using, create it as a smart list outside you report to get the total added to the campaign and then use the report to assess the numbers of those that engaged with the various assets.