You'll be staying at one of my favorite Disney World resorts: Port Orleans Riverside! Yes, it's true that Riverside is a large resort (especially compared with its much smaller adjacent sister resort, Port Orleans French Quarter). But Riverside is a really lovely resort with beautifully landscaped grounds, a good table service restaurant (Boatwright's Dining Hall), a food court (Riverside Mill) and lots of fun recreational options, including a terrific swimming area ("Ol' Man Island"). Riverside is divided into two main sections, Magnolia Bend and Alligator Bayou. My family loves the Royal Guest Rooms located in the Parterre Place and Oak Manor buildings.
Early March is a good time to visit Walt Disney World in terms of both weather and crowds. The average daily low and high temperatures are 55 and 78, with the average being 67. Since you are not visiting during a national holiday or school vacation period (school spring breaks begin later in March), you should not have heavy crowds to contend while on vacation.
It is not more than a 10-minute walk from the farthest rooms to the bus loading areas. The buses are most crowded in the morning and evening (as guests are making their way to and from the theme parks at opening and closing hours). You will have a longer wait to board a bus during these times of day. The bus loop at Port Orleans resorts will normally include both French Quarter and Riverside, usually stopping first at French Quarter. In addition to the bus stop outside the Main Hall (Sassagoula Steamboat Co.), there are also stops at the West, North and East Depots.
Best wishes for a magical vacation! Don't hesitate to stop back to visit us again here on the Moms Panel with any additional questions before your trip.