Before, you just step off the train, and there would be a "babushka" to take you to a room for rent. I wonder if it's different now.

You don't state your target budget for a room, but there is a nice boutique hotel in Yalta called the Vremena Goda (The Seasons). http://www.hotel-seasons.com.ua/en Generally, there is someone there that speaks English.

We also once stayed at the Oreanda, but their prices have become pretty high. The Yalta Hotel is typically the cheapest, but not as nice or as close to the seawalk as either of the others. You may also want to google the Bristol Hotel which is on the seawalk, but I've never stayed there.

On the way to Sevastopol from Yalta, there is a war museum and memorial . They also have some large equipment (tank/cannon) on the outside that people can inspect. It is near a very small church that is also interesting to take a look at inside.

In Sevastopol, within walking distance of Chersonesus, there is a Crimean War diorama -- it is in a large white building, somewhat non-descript. But, it's been quite a few years since I was there, so it may have changed.

The Livadia Palace (Yalta Conference) and Vorontsov's Palace are both accessible by the ferry system which operates during the non-winter seasons. The ferries stop along the Yalta seawalk, not far from the Oreanda Hotel, and at the Yalta Hotel. But you can also take a car to these places as well.