This invention relates to a lawn mower. In certain example embodiments, the lawn mower includes one or more of: (a) a cooling baffle for efficiently cooling a hydraulic fluid tank and/or fluid therein using air flow caused by a combustion engine used for driving mower cutting blade(s); (b) improved cockpit structure including fenders; (c) improved drive wheel(s) adjustment structure or assembly; (d) improved idler arm assembly for use in connection with the cutter deck and/or pump driving belt; and/or (e) improved hose routing structure.