Can I see my sales grouped by week or by month instead of by day?

Yes, on the Sales by Date report.

1. Open Marketing → Marketing Home and click the Reports tile under Measure.
2. Click View report → next to Sales over time.
3. Pick your period with the date picker.
4. Click Day, Week or Month on the right.

The chart and the table regroup straight away. Each row shows the start date of that day, week or month, with its Orders and Revenue. Click Export CSV to download the same grouping.