Using OSM standard tile layer (via OpenLayers) in commercial application

Hi,

I am using OpenLayers library for embedding maps into a commercial browser application. I am using OSM as tile server (https://openlayers.org/en/latest/examples/simple.html ) with OpenLayers API. The embedded map contains some markers with tooltips. I want to embed OSM map () into a commercial browser application. Open Layers has BSD 2 licence and using the OSM tiles ( http://www.openstreetmap.org/ ) are under the CC-BY-SA license.

Below are my queries:

1. Can I use OSM via OpenLayers in commercial application ? If yes, what should be the licence of the commercial product ?
2. Should I display the credits "© OpenStreetMap contributors" in the embedded map ?

Thank you !