The latest features make remote DJ's work well but are included in the "Advanced Scheduling Module".
This also includes advert management but isn't free.
If you want to have remote DJ's withoyt the subscription to the "Advanced Scheduling Module", before that came along (which works better than my solution) I wrote up how to have remote DJs.
Have a read through this.
If you have any questions about this process, if you ask at the end of that article it will keep discussion of this process together.
I can't easily think of a commercils scheduling workaround although if it is a fairly random selection you could have a track group called commercials and schedule from them in a clock.
The whole system is well documented either by the manual or the various YouTube videos.
As with all powerful software there is quite a learning curve, particularly with getting the scheduling to do what you want, but overall it's good and very stable.