not sure if the exact answer that you want but here goes
at work we have got loads of road and track
The track is a mix of ikea / tesco / lots of brio and i think a job lot from lidl as well and ELC
we have an ELC level crossing which has track AND road on it
I THINK all our road is ELC
we have an ELC carpark / garage type thing, which includes a car wash AND an ELC '999 station' (ie a little garage for a police car ambulence and firengine.)
It all joins with each other fine.
I think the brio track is the best.... some of the other tracks have plastic bits which you have to insert (and sometimes are either really difficult OR fall out, though id say about 70% are ok and going in and out easily enough) apart from that the track all links up fine. (although the brio track does seem the best its so much more expensive not sure its best value IUSWIM)
as for trains we have lots of genuine brio trains and other wooden one, for example the tesco trains made for the tesco track... which is almost identical to the brio track.
We have lots of vehicals... some 'Thomas' ones which i think are brio, loads of wooden ELC vehicals / lorries etc etc, and they all fit on the track and road. (also the road has a wedged bit in the middle that the trains can use too)
also have some cheeper metal / plastic 'typical' cars and some of them fit and some dont.
Upstairs we have the Tomy blue 'thomas' track... this definitely does not fit with any of the wooden track. i think the trains from that track dont fit properly on the wooden track either... though the brio etc trains drive quite happily on the blue tracks.
Hope that helps