The transition of the energy grid into a system with higher shares of renewable energy production requires careful investment planning while considering operational characteristics of generators. Generation Expansion Planning (GEP) is used for finding optimal investments, while Unit Commitment (UC) can be used to limit generator operational capabilities, such as via ramping limits, for more accurate modelling. The system may be extended to model custom thermal generator capabilities at the time of their start-up or shut-down, where they may differ from traditional ramping, promoting more precise modelling. However, the inclusion of such detail requires careful managing of model complexity to keep solving time feasible, which can be done with techniques such as Clustered Unit Commitment (CUC), and clustering time blocks while allowing flexible resolution combinations. The latter is known as Fully Flexible Temporal Resolution, and promises managing of model complexity via temporal resolution reductions, while maintaining modelling versatility. The paper targets the unexplored area of including Start-Up and Shut-Down (SU/SD) capability ramping limits alongside a fully flexible temporal resolution in a GEP & CUC model, and contributes by examining the effect of the new capabilities on the run times, investment and operational solutions, and the total system cost of a model with enabled Battery Energy Storage System (BESS) investments. The resulting findings show that the inclusion of the SU/SD capabilities has little effect on the investments and total cost of the model, significantly increases computation time, yet has a noticeable effect on the operational schedule of generators.