1. The first piece you can see here proves that you don’t need 4 strings – 3 are enough, if you open and end a piece on a gimbri.
2. You also don’t need a lot of chords – sometimes one chord is enough to totally rock da house. Hear the second one, which Marcus announced in perfect French.
3. and 4. They continue with Miles’ “Tutu“. Marcus, who is about two and a half years younger than me played that in 1986 with Miles, and here (at around the 33 minute mark) they swing like the devils, and play some really nice hard bop and cool jazz lines, just as if Miles would be present. And during the bass solo they switch to Marcus’ own “Blast”, the opening track from his 2008 album “Marcus” (and also on his 2007 album “Free“).
No, you don’t need much. Just keep practising for some 40+ years, and play as much as you can. See his discography.