Thanks for the initiative, @pxalcantara! We already opted-in for Hacktoberfest on all Ignition and Gazebo classic repositories and we’re looking forward to all the contributions!
I’d just like to point out that we have issues labeled “good first issue” which should be especially nice for newcomers to work on. I’ll also leave the link to our contribution guidelines here so people know where to start from.
Sure, I think they could be interested in participating 
I know that @Sarathkrishnan already got some pull requests in this month This year we also had @AmrElsersy, @marticres, @mihirk284 and @Mohamed_Ahmed. Last year we had @mingfeisun, @shiveshkhaitan and @mukulkhanna.