ECDSA signing vs generating public key
Is it a "simple" multiplication (such as 5*5 = 10) or the same way we multiply k by G to generate a public key?


It's multiplication modulo the curve order.  For example, if dA = 9, R = 7 and p = 13, then dA * R = 9 * 7 mod 13 = 63 mod 13 = 11.