Castle and Tekin are the leaders right now for 1/8th brushless ESCs. LRP and Orion have released their 1/8th controllers recently, but it might be awhile before the jury is back on how solid they are. There is also Hobbywing, the Novak HV systems, Quark, Speed Passion, and Losi Excelorin. I'm sure there's a few more that I'm missing. My only personal experience is with Castle's Mamba Monster, and you definitely can't go wrong with that; quality product and excellent support.
RC-Monster is a leader in brushless conversion. Check the shop and forums for anything you need. They mainly cater to buggies, truggies, and monster trucks, but there is still a good deal of info from people who do 1/8th on-road.