NG+: Can I use Striker just to do the ditman glitch and equip the grenade to run after the ditman glitch? (as shown in the re4central .com rules).

NG: Buy Striker in chapter 4-1 and get any grenade to equip?

(I have this question because re4central.com is another site and if all rules of this site are the same as speedrun.com)

As shown in the images below:

Yes for both NG+ and NG you are allowed to equip anything you want as long as you don't use it as a weapon.

But one doubt Carpenter, I can make upgrades to the pistol/shotgun in NG?

Yes absolutely, on NG you can upgrade your chosen weapon as much as you want in the merchant and on NG+ obviously you can have it fully upgraded at the start of the run.

OK, thanks for the information.

You can even re-sell the weapon if you are down to 0 ammo, so you can have one full clip of ammo again.