"1) Replace shock /w aluminum rigid"
Will slow you down everywhere except smooth ground. Bone up for a decent 3.5lb fork with a lockout for the climbs.
"2) Remove the front derailleur /w shifter"
What's a /w shifter? (I am all 'bout the 1x9 setup) Removing the front der., shifter, and rings could save you 1/2lb or so. In the grand scheme of things...that ain't spit.
"3) Drop two chain rings / reduce chain length, depending on which rings I drop (wont save much weight, but I wont need such a long chain if I use a smaller chain ring)"
Keep the middle.
"4) Get lighter tires when my current ones wear out."
Get some Kenda Nevegal 2.1" DTC's.
The most noticeable weight savings will be a good/light wheelset and some decent meats.
30lbs really isn't that bad unless you're a whiny-weight-weenie.