Pre Sales Help

Hello my name is lee i run a uk based record label and events company i have been looking to turn our site from online store to multi store mainly so other labels can sell digital products on our site some questions i have in regards to the cs multi vender demo are.

1 if i start to build my site and it switches to free mode and i want to carry on with the perchuse of your product would my site be how i built it before the free mode kicked in.

2 is this the best option on the market ?

3 is it stable for large amounts of digital sales ect

regards lee