It is a drawback to not have a car at Denali. There really are no hotels within walking distance of the train station, especially with luggage. But there are several hotels and lodges with transportation to/from the park. Not having a car means you are limited in your lodging options. It also means you can't get onto early buses into the park. You also can't drive the first 15 miles into the park in the evening without a car.
>>2. They'd like to go on some guided tours of the park and also be able to do some hiking on their own on the trails located inside the park.
>>3. Are there any tours that you would recommend at the park?
I would avoid "tours" and concentrate on "shuttle buses" in Denali. Most all shuttle bus drivers give excellent commentary. They are MUCH cheaper than the tour buses and you can get off the bus to go hiking on your own. Note - there are very few formal trails in Denali NP. You just get off the bus and hike on the trail-less tundra. The bus drivers and park rangers are an excellent source of information for good places to hike. The only real trails in the park are near the entrance. They can be nice, but limiting. There is one trail near Wonder Lake but there are so many other great areas in the park to hike. Check into the 3-for-2 shuttle bus tickets offered if you call to make your reservations. That will give them three days on the shuttle buses for the price of two.
You can check the Top Questions about Denali in the Denali forum on Trip Advisor. There is a list of lodging options near Denali that have transportation to the park.
When will they be in Alaska and for how long? What are their interests? Having 4-5 days in Denali is great but it is very worthwhile to see places like Seward, maybe even a glacier cruise from Whittier, etc.
Too bad that they will miss being able to stop along the drive between Denali and Anchorage. You might consider looking at the cost of a one-way car rental between Fairbanks and Anchorage (not cheap I know) and taking the train from Anchorage to Seward and back. It is much easier to get around Seward without a car than Denali. When comparing the costs, realize you can probably get lower-priced lodging near Denali if you had a car. Also realize that the flexibility of a car including stops you can make, etc. has value that is hard to put a pricetag on.