dude ur doing wayyyy to much work.
1.) the black plastic covers on the back of your headlights are clipped in with 2 bars gently pull the bars apart and the plastic cover will come off.
2.) after you have the plastic covers off you should be able to see your headlight bulb take the wiring harness off of the headlight pull gently it will come just need a lil elbow grease.
3.) after you get the headlight wiring out of the way there is another metal bar holding the headlight in place look for a screw holding it in (DO NOT UNDO THIS SCREW) on the opposite side of the screw is the retaining point you just simply push forward and down on the retaining clip to get it to come undone.
4.) after the retaining clip is loose take out your old headlamp and put the new one in (DO NOT TOUCH THE BULB). after you have positioned the tab with the flat side up into the headlight assembly properly it should sit flush.
5.) After you have the headlight in position bring the retaining clip back to where it was push in and up to make it lock.
6.) connect the wiring harness to the bulb
7.) put the plastic cover back on and fasten the 2 retaining clips back into position DONE! now go have a beer or do the other side lol
as for the driver side (battery side) u shouldnt have to move your battery i have 3 dubs in the family and never have i undone the battery to change a headlamp. it just takes patience and a flexible hand.
as for that mechanic 1.) yes he is a moron 2.) hes probably new 3.) not all mechanics r morons (points to self)