Tom,
I'm not up to par on the Mobile App yet however if I remember correctly you can use advertisements but don't hold me to it and ask on vbulletin.com or simply wait for someone else to chime in

.
Now I can answer the question about migrating SMF - Once you purchase vBulletin your able to access the members area - This is where you download vBulletin, any new patches and also what they call Impex. Impex allows you to transfer a different forum in your case SMF to vBulletin! Now bear in mind it won't bring over your current style, advertisements or customizations and things of that nature however it will import your users and forum content which imo, for a free script it does a fantastic job and your able to build your community in vBulletin from that point forward utilizing all of it's features.
You can find more information about Impex here:
https://www.vbulletin.com/forum/show...-What-Is-ImpEx
https://www.vbulletin.com/forum/foru...-Import-System
https://www.vbulletin.com/docs/html/impex