First course and trim question

Crackers

Hi,

On my shed I am putting shingles on.

1) Do I need to trim the tabs off the first course, or can I simply install the first row upside down (ie: tabs facing up the slope of the roof)?

2) Do I need to install the aluminum trim (looks like the letter "L", used to keep the water off the side of the roof) both on the bottom of the slope of the roof as well as up the sides?

Thasnk!

the roofing god

on a 3-tab roof ,cutting off the starter tabs will leave the sealant at the bottom edge of the roof,which works well against wind damage,the metal you describe sounds like fascia cover not eave flashing,I install a 3"x3" (rt. angle type)flashing custom bent to slightly less than the roof pitch for a snug fit,which the gutter screws into the bottom face and Ice&Water shield adheres to the top of onto the roof sheathing---for side("rake eaves") flashing install your underlayment first,then install a dripedge flashing ,typically referred to as f-4 1/2 flashing at supply houses