Pump, sump and elbow on the intake

Small plumbing question for you, plumbing experts... :-)

When I connect return pump (Little Giant 3-MDQ-SC) to my sump,
should I keep the pump intake stright from the bulkhead or can
I give it 90' elbow to have the pump parallel to the sump wall?

The pump is about foot long, inluding nessecary reduction
inbetween the pump and the sump (I have 1" bulkhead and 3/4"
female intake on the pump) it would take less space in my
cabinet if I can add an elbow right after the bulkhead...
The tank is 30g and I need as big sump as possible to dilute :-)

Also, the pump base has 4 mounting holes. Am I supposed to
drill 4 holes in my cabinet floor and screw the pump permanent?
What is the best way to install it asuring the quietest operation?

Any advice?