A few 01 DC build questions

Purchased a 2001 double cab on friday and it'll be my daily driver. I won't ever be doing any hardcore off roading, or much of any off roading. It might see a few mountain roads on the way to camping. I'm looking to get the best fuel mileage possible, as it will see a lot of highway. Unfortunately I have to wait until at least the 18th to see it with my own eyes, it's it being fixed (new ball joints, bracket holding gas tank is cracked or something).

My question is: What kind of mods and aftermarket parts would you recommend?

I will be retrofitting with projectors (morimoto minis) and replacing the rear tails with led (suggestions?).

I'm thinking about getting in on the wet okole group buy.

New floor mats (http://www.autoanything.com/floor-mats/64A2002A0A0.aspx)

Probably Deck plate mod (would cai be better? If so, which one?)

New drop-in air filter (k&n or something else?)

New battery (best for cold weather, i'm in canada it'll probably get close to -40c some days, also good for running stereo w/amp & subs)

Speaker upgrades (can you fit a 6x9 in the front or rear? Which ones are good? Is under the driver seat the best place for an amp? sub box likely behind the back seat, sub recommendations )

window rain guards (http://www.autoanything.com/deflectors/61A2923A0A0A1861359.aspx)
Tonneau Cover

i'd like a very small running board or bar for knocking shoes off in the winter before you get in

Do stock size tires give the best mileage? Which ones would you recommend? Which winter tires?

Here is what it looks like:
http://www.tacomaworld.com/forum/attachment.php?attachmentid=71723&stc=1&d=1283914457

Thanks!!