using something connected to a sata or m.2 connector would be safer than using a USB-connected drive due to how Qubes recommends isolating all USB connectors. Looking at the specs, it should be possible to add a second internal drive. If you want to seriously use Qubes, you'll want to have at least 16GB ram, though, and your laptop CPU will likely be a bit of a bottleneck, due to the likely to be low core/thread count. Aside from that, you should be fine though.