The SS lines are identical to the Rubber ones, only SS and usually longer. Spray the fittings on the stock hoses with some PB Blaster a couple times a day for a couple days prior to replacing.
The solid pipes are stupidly expensive from Rover suppliers. Just because they're pre-bent. Any local auto parts store will have varying lengths of 3/16" Bubble Flare piping. I think a 12" piece is just long enough for the front between the caliper and flexible line.
The rectangular fitting on the rear is not a vlave of any type near as I can tell. I pulled the one off my parts truck and blew some compressed air into it. Air in one hole only exited through one other hole, and vice versa. Which was disappointing because I wanted to use it as a T fitting.

 

I think I'm going to get the +2" ss lines for my future lift. And I've been looking for those pipes on RN but can't find them. I went to brake and then pipes. I'll look again tmr, if not I'll call

 

Don't buy the lines. Just get a flaring tool, some fittings and tubing, maybe a pair of forming pliers to make the really tight bends, and you're good. The initial outlay is more because you're buying tools, but in the long term you can make your own metal lines for pennies on the dollar compared to buying pre-made lines.
I use the OTC 4504 ISO flare tool and Eastwood Brake Line Forming Pliers
You can get all the line and fittings you need from Fedhill.