Confused with train tickets planning

I�fm a bit struggling with understanding which train tickets / passes I should buy, I find everything so confusing (ps I don�ft have a jr pass).
I have some questions hopefully someone can help me here:

- Tokyo -> Kyoto with Shinkansen. I�fm finding a bit complicated to buy the ticket online, can I buy it in person when I will be in Japan? I�fll be travelling end of November with 2 oversized luggage (we are 2 people)

- Hakone Pass - Did I understand correctly that if I want to from Shinjuku to Hakone with the Romancecar, I should buy the pass for Hakone only, and separately buy the romancecar from Shinjuku to Hakone yumoto (back and forth)?

- Nikko and surroundings - We are planning to go:
day 1 - Tokyo -> Yunishigawa Onsen 
day 2 - Yunishigawa Onsen -> Nikko (go around) -> Tokyo (evening) 
I was initially thinking to buy the Nikko Pass but it wouldn�ft cover my trip on day 1, correct? I will take the Limited Express Revaty
Is the Nikko pass worth it for only 1 day / half a day? 
Does the Nikko Pass cover the trip from Nikko to Tokyo? I don�ft understand it from the website. It seems like it cover the trip, but then I read that for the express train an additional ticket is needed. But the express train is the way to get there so why they say it�fs included 1 round trip? 
Can I buy the tickets (both Nikko Pass and the train ticket for Yunishigawa Onsen) when I�fm in Tokyo or do I need to do it online? I�fm afraid it will be full and there won�ft be available seats anymore)

- Sagano Romantic Train - I wanted to buy tickets for the end of November / beginning of December but it�fs all booked out! :( checked in the official website and on klook. Any chance to buy them anywhere else?

Regarding Shinkansen ticket, yes you can easily buy them at a JR station (best from a machine) when you are here. With two oversized luggage you need to buy the last row. It�fs a special menu point when buying the ticket at the machine.
I would however rethink if you need two oversized luggages. Hotel rooms are small in Japan so you�fll be dancing around your luggage every time you enter your room. Try packing lightly and consider washing at a hotel (check but many hotels have washing machines). Some people complain that this takes time. But it doesn�ft really. You just do it in a time you are in your room anyway.

I don�ft know enough about the Nikko and Hakone passes to advise.

Regarding Sagano railway there was recently a different post about it that answers your question. It�fs not surprising that it is sold out end November being it peak time for koyo.