HOW MANY PICTURES CAN I HAVE ON THE MLS? 
Depends on your package you purchased as to how many pictures are included - If your pkg doesn't include "Enhanced Showcase Listing" - consider upgrading for the small fee.
The below is the max number of pictures your MLS allows:
REIN MLS (VA Beach, Hampton Rds and Tidewater area) = 32 pictures
MRIS (Northern VA - Fredericksburg and Surrounding Areas) = 30 pictures
WAAR (Williamsburg and Surrounding Areas = 30 pictures
WRAR MLS (Lynchburg and Surrounding Areas) = 25 pictures
CVR MLS (Richmond and Surrounding Areas) = 24 pictures
RV MLS (Roanoke Valley and Surrounding Areas) = 50 pictures
CAAR (Charlottesville and Surrounding Areas) = 25 pictures
HRAR (Harrisonburg and Rockingham Areas) = 30 pictures
SWVAR / NRV (Montgomery and Surrounding Areas) = 25 pictures
Call for other MLS Systems.

Slideshow pictures are critical to buyers - they want to see if they like the home before they sit in traffic to see your home. If you don't have pictures of certain rooms - the buyer wonders what is wrong with that room that you are not showing it. It may be more cost effective to add the Realtor.com showcase listing to your package so your pictures will go on their site as well as all the others.

HOW MANY CHARACTERS/SPACES IS THE INTERNET REMARKS (THE DESCRIPTON OF MY HOME)?
Depends on which area you are in -
300 Characters/Spaces in the REIN MLS (VA Beach, Hampton Rds and Tidewater area and Surrounding Areas)
400 Characters/Spaces in the MRIS, WAAR & RV MLS ((Northern VA - Fredericksburg and Surrounding Areas) (Williamsburg) and (Roanoke Valley).
500 Characters/Spaces in the HRAR MLS (Harrisonburg and Rockingham County)
800 Characters/Spaces in the CVR MLS (Richmond and Surrounding Areas)
1000 Characters/Spaces in the SWVAR NRV MLS (New River Valley and Surrounding Areas)
1000 Characters/Spaces in the WRAR MLS (Lynchburg and Surrounding Areas)
 

HOW MANY CHARACTERS/SPACES IS ALLOWED FOR THE DIRECTIONS TO MY PROPERTY?
Depends on which area you are in -
100 Characters/Spaces in the REIN MLS.  (VA Beach, Hampton Rds and Tidewater area)
120 Characters/Spaces in the WAAR MLS.  (Williamsburg and Surrounding Areas)
200 Characters/Spaces in the RV MLS.  (Roanoke Valley and Surrounding Areas)
215 Characters/Spaces in the CVR MLS. (Richmond and Surrounding Areas)
240 Characters/Spaces in the MRIS MLS.  (Northern VA - Fredericksburg and Surrounding Areas) 
250 Characters/Spaces in the WRAR MLS (Lynchburg and Surrounding Areas)
400 Characters/Spaces in the HRAR MLS (Harrisonburg and Rockingham County)
500 Characters/Spaces in the SWVAR NRV MLS (New River Valley and Surrounding Areas)