Having the camera sit still:
If you have multiple points, the mod will try to put a smooth curve through them which will result in a path segment where you'd expect no movement to already contain some movement just so that when the camera actually starts moving, it does so smoothly.
If you the camera to actually stand still, put down two keyframes at the same location and change the interpolation type for the first one. That way, the mod will effectively create a separate path to interpolate just for that segment and because there's no change in position in that segment, the camera will be completely fixed.
You'll probably find the path preview (default key binding: H) to be of use to prevent the interpolated path from going into walls and such.
Also make sure to use Catmull-Rom-Spline interpolation (default for latest ReplayMod version) as other methods might behave in really unexpected ways if you don't know exactly how to use them.
Player not moving:
You probably didn't fully understand time keyframes. Make sure to place the first one at 00:00 while you are at the time in the replay where you want to start and only put down the last time keyframe (assuming no timelapses, you only really need two time keyframes) at 00:30 (or however long your video should be) while you are at the time in the replay where you want to stop. So to make it absolutely clear: If you do not move through time while placing the time keyframes, time will not move in the video either.
"Since the mod has no option to remove hud when rendering":
I have no idea what you mean by that. We don't render the hud. We are unable to do so for some of the rendering modes (i.e. where should we've placed it during 360 rendering?), and because GUIs are generally not needed for cinematic videos, we dicided to just never render the hud, regardless of rendering mode.
Crash when moving back in time and always in first person:
You've asked that before in a different thread where I've already answered you.
When I said hud I mean like you know you press f1 to hid your characters hand, inventory bar and etc? I need that option so I can render it cause my other mod apparently treats the replay like the game so it shows me the energy bar that it has and it shows when rendered.
time keyframes: cant do that. Like I said every time I try to go to the beginning it keeps crashing. So the time keyframe thing is impossible for me. Unless it doesnt exactly have to BE in the beginning. Not to mention I have NO idea how to even find the spot I need to put the keyframe for the camera moving. I go to a spot before the movement and placed a time keyframe but once there I dont have the slightest idea where to go from there. It doesnt have a way to show me what happens when and where. I can only gamble by placing it randomly and hope for the best.