I would avoid a lens brush. Any contaminant on the bristles will end up on the lens, causing smearing & other problems. My 10+ years working in retail camera stores, plus teaching a class in basic photo & doing weddings on the side have taught me that.
As far as canned air, the risk is the propellant. Shaking or tilting the can will cause the propellant to some out, and really make a mess of things. As lsiberan suggested, use the canned air on the internal parts that are NOT in the light path. I’m not familiar with projectors, but if there are mirrors, CCD’s, prisms…anything the light passes through, you’re better off using the blower bulb. You’re just blowing air on the components to get the dust off.
If it’s not too big a hassle, can you take the projector off its mount? This will give you much easier access to the internal parts (if they are in need of dusting). I find the combination of canned air and a vacuum hose most effective. Give a blast of the canned air, and see where the dust comes out. Position the end of the vacuum hose there, and suck up the dust as it comes out, rather than letting it settle somewhere else inside.
The cloths you show are good, but you should also order/buy some dry lens cloths. The pre-moistened cloths will leave a little residue, which can be removed with dry lens tissue. AVOID fabric lens cloths. They easily become contaminated by the oils on your fingers, which then smear onto the lens. And yes, it’s best to keep a cap on the lens when not in use.