transfer to Tenzan or Hakone Kamon, which is better if I like to relax together with female?Neither bath seems to be offering private baths. So, unless you are a woman, you will have to bathe in separate baths.
or is it better to go to Hakone Kowakien Yunessun which feels more touristy?
It does not feel more touristy. It just feels less than a hot spring, especially the section with the swimming pools.
1pm Hakone Yumoto to Gora, Tozan bus or railway is faster?
There is no direct bus to Gora. The train is better.
Gora to Souzan by cable car, return
Gora to Gotemba outlets - should I wait for the Hakone Tozan direct bus or transfer to Sengoku to take the Odakyu Highway bus?
It makes no sense to take the cablecar to Sounzan and back. The ride is not interesting. If you have the time, I would recommend to take the cablecar and ropeway all the way to Togendai and catch the Odakyu bus to Gotemba from there. Alternatively, there are a few direct buses to the outlet from Gora.
I am afraid these bus are full and can't get on, do I need to reserve?
I don't think you have to worry about these buses being full, unless you travel on the evening of the the last day of a weekend or holiday.
Is this day trip too ambitious?
No, I think it is feasible, especially if you like to travel at a fast pace.
