They can be played together. The key thing is knowing whether you will be playing a standard, quick change or slow change 12 bar blues. If you have a looper record one on the looper and play over the loop with the other or alternatively loop Justin playing the 12 bar blues progression and jam along with Justin using the shuffle riff.
If you’re asking can you do a solo guitar arrangement that plays both the riff and chords. Yes, for example you could play the 12BB riff and play full chords on bars 9, 10 & 12. In terms of strumming patterns you get various strumming patterns employing the swing feel and also straight feel (for straight blues).