Firstly welcome to the forum.
The rocker cover gasket is so easy to fit i think a child could do it!!!

Honestly it really is that easy.

The brakes do sound like they may need bleeding, could also try new pads mayb, if your saying the discs have loads of life left in them.

The burning smell is probably oil dripping onto the exhaust manifold, especially if the rocker cover gasket has been leaking.

Hope some of this helps

Cheers Macca