Smf and Mybb Comparison: Question

[AquaSaberwolf]

Hello friends, We are planning to open a forum site soon. We have made decisions regarding the name and hosting. Instead of paid scripts like Vbulletin and Xenforo, we are considering starting with free alternatives like Smf and Mybb. We have a few questions in mind. Can you help? 1- For SMF or MyBB, which one has more free or paid support and themes? 2- If our project is successful, can we transfer our forum from one of these to the paid Vbulletin or Xenforo? 3- Lastly, are there any WordPress themes that can serve as an alternative to forum scripts? Or do you have any other suggestions in mind?