The answer to all of your requested feature changes is "Yes, but it will take some work". I would recommend that you go to the
Frictional Games Discord Channel and ask there for advice on how to accomplish them.
For your asset requests, they are also possible but you might have problems finding someone to fulfill 2, particularly if you are asking for someone to do this for free. Your best bet is to use a service like
Mixamo or
Fuse and find/generate the model you are looking for, match it with some preset animations, and then go to the discord server and ask for advice on how to convert those files for use in HPL3.