If you bought all that gear you would be faster because your wallet would be much lighter.

Otherwise you wouldn't really notice any difference.

Cycling shorts with a chamois makes sense most for road riders who don't move a lot on the saddle---they are most prone to chafing. An SS rider who is always up and down is less likely to develop saddle sores.

The jersey won't catch as much sweat and will pass more air, but unless you are riding in the tropics the effect is minimal. I find jerseys a little bit more comfortable on really hot humid days but I (and the rest of the world) rode in cotton T-shirts for decades with no adverse effects.

The biggest gain with cycling shoes is the stiffer sole. There might be (depending on whose Internet post you believe) some tiny percentage gained on the upstroke with clips but not very much by even the most optimistic estimates.

On the other hand, your feet will not cramp so much after you ride, and your calves hopefully won't hurt quite so much, as cycling shoes have very stiff soles.

A reasonable low-cost alternative here is the rat-trap approach, with the traditional toe-clips and straps---you can gauge for yourself how much faster you go while attached to the pedals, and decide if the several hundred-dollar investment in pedals and shoes is worth it.

Gearing will make a huge boost in efficiency ... not necessarily in pleasure.Some folks love pounding it out on single-speeds ... and power to them. But unquestionably you will go further and faster on a geared bike---IF you use the gears properly.

However, the cost of adding gears to an SS frame is Way beyond all that other gear ... you would be best off buying a whole new bike---(which is pretty much the answer to all questions on BF, as a poster pointed out.)