<p>Intelligent reflective surfaces (IRSs) have attracted significant attention due to their exceptional capability to enhance the capacity and coverage of wireless networks by intelligently reconfiguring the wireless propagation environment in a controlled manner. Due to their immense potential to revolutionize wireless paradigms, IRSs are envisioned as an emerging technology for sixth-generation (6G) communication networks. To analyze a practical scenario, we study the performance of finite alphabet signals in the context of IRS-assisted wireless communications over Rayleigh fading channels, which is in contrast to the majority of works in the literature that consider Gaussian input. Motivated by the high data rates and enhanced power efficiency of Quadrature Amplitude Modulation (QAM) and its variants, we have employed it as channel input. We analyze the impact of modulation parameters on the achievable rate by implementing a Monte Carlo simulation. We infer from the results that even a small number of IRS elements can provide a substantial rate gain, especially when compared to an additive white Gaussian noise channel, particularly when the signal-to-noise ratio (SNR) is low. Furthermore, we also consider the gaussian multiple access channel (G-MAC) in an IRS-assisted wireless channel for M-QAM inputs and evaluate its achievable rate, which clearly show improved sum rates. Security, being one of the key concerns of 6G wireless networks, has been considered in the proposed work, and we compute the secrecy sum rate for IRS-assisted GMAC with an eavesdropper for the different variants of QAM, which has not been reported in any previous work. Since it is well known that there is no closed-form expression for mutual information with finite constellation, we try to find a bound on the achievable rates. To gain more practical insight, we derive a lower bound of sum rate for IRS-assisted two-user GMAC for M-QAM inputs, and compare it with the simulated results. Next, we have also evaluated the energy efficiency of M-QAM variants in an IRS-assisted environment with and without security and also evaluated the inner bound to determine the performance benchmarks. The numerical results reveal that the bound though not so tight but helps in establishing performance benchmarks. In addition to security, energy efficient communication is also a key concern for next generation communication networks. We compute energy efficiency for various practical scenarios for IRS aided Multiple Access Channel, with and without security constraints. We observe that the SNR requirements for energy efficient communication systems are different from rate-efficient systems. In particular there is tradeoff between rate and energy efficiency, which can guide the system designers while choosing optimum modulation scheme for communication network.</p>