moving to a Walker from Deere. got a MT26, have 74" deck / gear boxes questions

I have a massive John Deere 1445 with 72" cut. I fight getting under my trees and I have 30-40 trees. Anyhow, I was attracted to the Walkers low slung design and picked on up. I got the MT26 with 74" deck. My questions are centric to the deck system. I have never seen anything like it. They look all tied together via sealed housings around the shafts. I assume oil can flow across all. So do I check/ add oil in 1 specific place? Also, I have 1 blade that has some bearing play. Are the gear boxes serviceable to the extent a guy can remove it and replace a bearing, seal, etc? Lastly, where/ what is best blades to replace the 74" system with?