"What would you use besides conses to represent s-expressions?"
What are s-expressions? I thought their main aspect was the way they used lists to represent user-extensible syntax forms (macro forms, function applications, fexpr applications). I'm not a fan, but even if we assume s-expressions, they could always use some other implementation of lists.
"I wonder if there's a way to merge quote and lambda into a single operator."
Do you mean like in PicoLisp, where all user-defined functions are lists containing their code, and applying a list causes it to be interpreted as a function?
I don't like it, 'cause you don't get any lexical scoping this way. It probably makes more sense in Factor and Joy thanks to the lack of local variables for run-time-created functions to capture.