New (to me) C4500 with a few questions

Hey guys, Purchased a 2004 Kodiak from original owner. Gentleman took great care of the rig and Installed some aftermarket upgrades. Currently has Kelderman 4-corner air ride, LED headlamps and some comfortable yet worn out aftermarket seats. It is my first "big truck" and its been fun to drive so far.

Interior questions:
I am going to renovate the interior. Either have all the seats reupholstered, or buy new seats. The current seat set-up looks like factory seat frames/stands with two captains and a center console. Does anyone know where I can find replacement seats such as the ones I currently have? In hopes of finding a more modern bolstered seat. Or should I remove the whole seat set-up and buy replacement air seats. If so, do they make plug and play brackets for this?

Does anyone make upgraded dash trim? Does this truck share anything interior wise with vans (i heard this might be true?)

Carpeting:
I am ready to purchase the stockinteriors.com carpet kit. Is this a good one?

Wheels:
Is there a pro/con to upgrading to 22.5 other then looks?

Tires:
245/70/19.5 - Suggestions on new Rear tires? I was looking at Hankook Smart Flex AH35. Can these be ran on rear? Says "however can also be used on drive axles", but didnt sound like a great fit on Tirerack.com.

Shocks:
I assume Bilstein is the best replacement shock without going overboard/custom. Saw Koni FSD. Any people test them?

Engine:
I have LLY engine. Is there any "bulletproofing" that I should do?

Truck Cover:
Anyone know if a company makes a car cover for this large a rig?

Thanks for any help! Looking forward to using this rig as much as possible